0001692115-26-000062 | 10-K | XBRL Viewer | Southwest GAS Holdings INC

Less: Income (loss) from discontinued operations, net of income tax

$ 435,180

$ 204,836

$ 155,517

200,344

(16,143)

15,523

Income from continuing operations, net of income tax

234,836

220,979

139,994

Adjustments to reconcile net income to net cash provided by operating activities:

Depreciation and amortization

330,724

303,095

295,462

Impairment of assets and other charges

71,230

Deferred income taxes

118,112

57,730

59,392

Gains on sale of property and equipment

(1,604)

(136)

Share-based compensation expense

14,631

11,372

6,228

Equity AFUDC

(5,809)

(6,597)

(1,951)

Changes in current assets and liabilities:

Accounts receivable, net of allowances

32,411

66,275

(38,387)

Accrued utility revenue

(5,000)

(3,600)

(4,900)

Deferred purchased gas costs

63,280

706,896

177,177

Accounts payable

13,172

(20,006)

(256,399)

Accrued taxes

(20,460)

2,152

(5,386)

Other current assets and liabilities

(97,689)

(57,160)

16,837

Changes in deferred charges and other assets

(62,028)

(47,914)

(32,046)

Changes in other liabilities and deferred credits

(20,415)

(27,890)

(76,610)

Net cash provided by operating activities of continuing operations

594,161

1,205,332

350,505

Net cash provided by (used in) operating activities of discontinued operations

(38,085)

150,448

158,706

Net cash provided by operating activities

556,076

1,355,780

509,211

CASH FLOW FROM INVESTING ACTIVITIES:

Capital expenditures and property additions

(807,866)

(846,590)

(765,871)

Proceeds from the sale of business, net of cash sold

1,022,483

Proceeds from the sale of property

5,306

21,377

Changes in customer advances

2,023

(5,995)

(8,905)

Other

(955)

(985)

(1,891)

Net cash provided by (used in) investing activities of continuing operations

(801,492)

(832,193)

245,816

Net cash provided by (used in) investing activities of discontinued operations

^[1]

776,678

(89,375)

(94,850)

Net cash provided by (used in) investing activities

(24,814)

(921,568)

150,966

CASH FLOW FROM FINANCING ACTIVITIES:

Issuance of common stock, net

19,727

8,884

251,759

Dividends paid

(178,509)

(177,628)

(174,574)

Issuance of long-term debt, net

847,759

Change in short-term portion of credit facility

(130,000)

51,500

(94,000)

Change in long-term credit facility and commercial paper

(50,000)

Issuance of short-term debt

450,000

Repayment of short-term debt

(550,000)

(1,822,748)

Withholding remittance – share-based compensation

(3,063)

(2,677)

(1,777)

Other, including principal payments on finance leases

(4,678)

(3,656)

(3,768)

Net cash used in financing activities of continuing operations

(846,523)

(123,577)

(597,349)

Net cash provided by (used in) financing activities of discontinued operations

528,244

(52,758)

(103,446)

Net cash used in financing activities

(318,279)

(176,335)

(700,795)

Effects of currency translation in discontinued operations

(127)

(624)

273

Change in cash and cash equivalents, including discontinued operations

212,856

257,253

(40,345)

Change in cash and cash equivalents included in current assets held for sale

23,803

Cash and cash equivalents, including discontinued operations, at beginning of period

363,789

106,536

123,078

Cash and cash equivalents, including discontinued operations, at end of period

576,645

363,789

106,536

SUPPLEMENTAL INFORMATION:

Interest paid, net of amounts capitalized

240,175

278,888

282,626

Increase (decrease) of capital expenditures in Accounts payable or Other current liabilities

16,614

(8,705)

(17,055)

Equity AFUDC capitalized in regulated operations plant

5,809

6,597

1,951

Continuing Operations

SUPPLEMENTAL INFORMATION:

Interest paid, net of amounts capitalized

196,875

200,623

184,284

Increase (decrease) of capital expenditures in Accounts payable or Other current liabilities

25,800

(6,100)

(22,753)

Equity AFUDC capitalized in regulated operations plant

5,809

6,597

1,951

Discontinued Operations

SUPPLEMENTAL INFORMATION:

Interest paid, net of amounts capitalized

43,300

78,265

98,342

Increase (decrease) of capital expenditures in Accounts payable or Other current liabilities

(9,186)

(2,605)

5,698

Equity AFUDC capitalized in regulated operations plant

$ 0

[1]	(1) Includes change in cash and cash equivalent of Centuri of $49 million for the year ended December 31, 2025.

Pension and Other Postretirement Benefits - Schedule of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2025 USD ($)
QRP
Defined Benefit Plan Disclosure [Line Items]
2026	$ 72.0
2027	73.0
2028	74.0
2029	75.0
2030	77.0
2031-2035	409.0
SERP
Defined Benefit Plan Disclosure [Line Items]
2026	3.5
2027	3.5
2028	3.4
2029	3.4
2030	3.4
2031-2035	16.2
PBOP
Defined Benefit Plan Disclosure [Line Items]
2026	5.0
2027	5.1
2028	5.1
2029	5.1
2030	5.2
2031-2035	$ 25.8

Segment Information - Narrative (Details) - segment	1 Months Ended	12 Months Ended	30 Months Ended
Segment Information - Narrative (Details) - segment	Feb. 28, 2023	Dec. 31, 2025	Aug. 31, 2025
Segment Reporting Information [Line Items]
Number of reportable segments	3	1	2
Southwest Gas Corporation
Segment Reporting Information [Line Items]
Number of reportable segments		1

Regulated Operations Plant - Schedule of Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 330,724	$ 303,095	$ 295,462
Gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 295,661	$ 274,556	$ 256,847

Receivables and Related Allowances - Narrative (Details)	12 Months Ended
	Dec. 31, 2025 state
Receivables [Abstract]
Number of states in which entity operates	3
Accounts receivable, extending period	1 month
Threshold period after inactivation for write-off of accounts receivable	2 months

Income Taxes - Schedule of Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from continuing operations before income taxes						$ 330,873	$ 254,136	$ 169,404
Southwest Gas Corporation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from continuing operations before income taxes	$ 5,098	$ 38,411	$ 181,750	$ 220,161	$ 225,259	$ 353,131	$ 304,765	$ 270,574

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Debt - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
Debt - Narrative (Details) - USD ($)	Jun. 30, 2025	Dec. 31, 2025	Aug. 31, 2025	May 31, 2025	May 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Short-term debt		$ 0				$ 680,000,000
Weighted average interest rate		9.23%
Southwest Gas Corporation
Debt Instrument [Line Items]
Debt covenant, additional debt amount could be issued		$ 4,700,000,000
Debt covenant, equity cushion relating to minimum net worth requirement		3,000,000,000.0
Commercial Paper Program \| Southwest Gas Corporation \| Commercial Paper
Debt Instrument [Line Items]
Commercial paper, maximum issuance capacity		50,000,000.0
Short-term debt		$ 0
Notes, 6.1%, due 2041 \| Debentures
Debt Instrument [Line Items]
Debt instrument, stated interest rate		6.10%
8% Series, due 2026 \| Debentures
Debt Instrument [Line Items]
Debt instrument, stated interest rate		8.00%
Long-term debt, gross		$ 75,000,000.0
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 300,000,000.0
Interest period	7 days
Long-term debt outstanding		$ 0
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Line of Credit \| Minimum
Debt Instrument [Line Items]
Commitment fee, unfunded portion	0.075%	0.075%
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Line of Credit \| Maximum
Debt Instrument [Line Items]
Commitment fee, unfunded portion	0.20%	0.20%
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Line of Credit \| SOFR
Debt Instrument [Line Items]
Debt, basis spread on interest variable rate	0.03839%	0.03839%
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 400,000,000.0
Long-term debt outstanding		$ 0
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation \| SOFR
Debt Instrument [Line Items]
Debt, basis spread on variable rate		1.125%
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation \| Alternative Base Rate
Debt Instrument [Line Items]
Debt, basis spread on variable rate		0.125%
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 150,000,000.0
Interest period	7 days
Revolving Credit Facility \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation \| Line of Credit \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		250,000,000.0
Revolving Credit Facility \| Revolving Credit Agreement Due December 2026 \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 300,000,000.0
Bridge Loan \| Revolving Credit Agreement Due August 2029 \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 30,000,000.0
Bridge Loan \| Revolving Credit Agreement Due August 2029 \| Southwest Gas Corporation \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	30,000,000.0
Secured Debt \| Line of Credit
Debt Instrument [Line Items]
Short-term debt			$ 225,000,000.0	$ 225,000,000.0	$ 550,000,000.0	$ 0
Debt instrument face amount	$ 550,000,000.0

Previously Issued Condensed Consolidated Financial Statements (Unaudited) - Narrative (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Aug. 11, 2025	May 22, 2025	Sep. 30, 2025	Jun. 30, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense				$ 79,865	$ 107,534		$ 96,037	$ 33,157	$ 29,410
Deferred income tax liabilities, net							977,312	857,982
Current maturities of long-term debt			$ 75,000			$ 75,000	75,000	0
Long-term debt, less current maturities			3,432,120			3,432,120	$ 3,433,012	$ 3,504,477
Continuing Operations
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense			7,039			71,172
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense				27,271	27,271
Deferred income tax liabilities, net			35,100	$ 27,300	$ 27,300	35,100
Current maturities of long-term debt			75,000			75,000
Long-term debt, less current maturities			(75,000)			(75,000)
Adjustments \| Continuing Operations
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense			$ 7,842			$ 35,113
Public Offering And Private Placement
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sale of stock, number of shares (in shares)	18,823,500	13,207,142

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Discontinued Operations and Disposal Groups [Abstract]

Dispositions (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Net Proceeds from Sale of Stock

The following table presents the net proceeds received by the Company for the sale of Centuri common stock subsequent to the Centuri IPO:


Secondary Offering Information	Net Proceeds (in million) (1)
May 22, 2025 public offering and private placement	$	224.6
June 18, 2025 public offering	224.1
July 8, 2025 private placement	22.0
August 11, 2025 public offering and private placement	355.2
September 5, 2025 public offering	524.0
Total	$	1,349.9

(1) Net proceeds, net of transaction costs

Schedule of Disposal Groups, Including Discontinued Operations

The gain on deconsolidation as of August 11, 2025, adjusted during fourth quarter of 2025, is calculated as follows (in thousands):


Fair value of the retained investment in Centuri (1)	$	533,636
Net proceeds received from the August 11, 2025 public offering and private placement	355,220
Carrying value of noncontrolling interest attributable to Centuri prior to deconsolidation	460,897
Centuri deferred tax asset adjustment (2)	(24,257)
Less: Carrying value of Centuri net assets prior to deconsolidation, including AOCI	(982,396)
Gain on deconsolidation of Centuri before income tax (3)	343,100
Income tax expense	82,650
Gain on deconsolidation of Centuri, net of tax	$	260,450

(1) Centuri’s quoted stock price is used for fair value measurement, which is classified as level 1 in the fair value hierarchy as of August 11, 2025.

(2) Represents adjustment of deemed capital contribution for the Company’s fourth quarter of 2025 results of operations and the filing of 2024 federal and state income tax returns according to the terms of the Tax Assets Agreement.

(3) Includes $120.2 million gain on interest sold and $222.9 million gain on the investment retained.

The following table summarizes the components of assets and liabilities of discontinued operations on the Company’s Condensed Consolidated Balance Sheets at December 31, 2024:


	December 31,
(Thousands of dollars)	2024
Cash	$	49,019
Accounts receivable, net of allowances	519,610
Other current assets	32,755
Total current assets classified as discontinued operations	601,384
Other property and investments, net	1,025,700
Goodwill	770,046
Deferred income taxes	52,376
Deferred charges and other assets	79,004
Total noncurrent assets classified as discontinued operations	1,927,126

Current maturities of long-term debt	30,018
Accounts payable	140,889

Other current liabilities	211,985
Total current liabilities classified as discontinued operations	382,892
Long-term debt, less current maturities	843,863

Other deferred credits	172,863
Total noncurrent liabilities classified as discontinued operations	$	1,016,726

Summarized results from discontinued operations were as follows:


(Thousands of dollars)	2025		2024		2023
Utility infrastructure services revenues	$	1,613,113	$	2,637,229	$	2,899,276
Utility infrastructure services expenses	(1,507,393)		(2,424,585)		(2,628,476)
Depreciation and amortization	(83,393)		(135,345)		(145,445)
Net interest deductions	(51,530)		(90,515)		(97,476)
Gain on deconsolidation	343,100		—		—
Loss on final disposition of retained interest	(9,688)		—		—
Other income (deductions), net	(135)		376		66
Income (loss) from discontinued operations before income taxes	304,074		(12,840)		27,945
Income tax expense	(103,730)		(3,303)		(12,422)
Net income (loss) from discontinued operations	200,344		(16,143)		15,523
Net income (loss) attributable to noncontrolling interest	(4,646)		6,021		4,628
Net income (loss) from discontinued operations attributable to Southwest Gas Holdings, Inc.	$	204,990	$	(22,164)	$	10,895

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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Discontinued Operations and Disposal Groups [Abstract]

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net income	$ 435,180	$ 204,836	$ 155,517
Defined benefit pension plans:
Net actuarial gain (loss), net of tax expense (benefit) of $13,114, $1,162 and $(765), respectively	41,526	3,680	(2,423)
Amortization of prior service cost, net of tax expense of $42, $42 and $42, respectively	133	133	133
Amortization of net actuarial loss, net of tax expense of $906, $1,834 and $319, respectively	2,869	5,807	1,014
Regulatory adjustment, net of tax benefit of $(12,844), $(2,360) and $(319), respectively	(40,673)	(7,473)	(1,011)
Net defined benefit pension plans, net of tax	3,855	2,147	(2,287)
Total other comprehensive income (loss), net of tax	9,008	(7,976)	455
Comprehensive income	444,188	196,860	155,972
Southwest Gas Corporation
Net income	300,308	262,096	228,412
Defined benefit pension plans:
Net actuarial gain (loss), net of tax expense (benefit) of $13,114, $1,162 and $(765), respectively	41,526	3,680	(2,423)
Amortization of prior service cost, net of tax expense of $42, $42 and $42, respectively	133	133	133
Amortization of net actuarial loss, net of tax expense of $906, $1,834 and $319, respectively	2,869	5,807	1,014
Regulatory adjustment, net of tax benefit of $(12,844), $(2,360) and $(319), respectively	(40,673)	(7,473)	(1,011)
Net defined benefit pension plans, net of tax	3,855	2,147	(2,287)
Total other comprehensive income (loss), net of tax	3,855	2,147	(2,287)
Comprehensive income	$ 304,163	$ 264,243	$ 226,125

Common Stock	12 Months Ended
Common Stock	Dec. 31, 2025
Equity [Abstract]
Common Stock	Note 8 - Common Stock Shares of the Company’s common stock are publicly traded on the NYSE under the ticker symbol “SWX.” Share-based compensation related to Southwest Gas is based on awards to be issued in shares of the Company. In November 2023, the Company and Southwest Gas jointly filed an automatic shelf registration statement (File No. 333-275774), or a Universal Shelf, which became effective upon filing and includes a prospectus detailing the Company’s ability to offer and sell, from time to time in amounts at prices and on terms that will be determined at the time of such offering, any combination of common stock, preferred stock, debt securities (which may or may not be guaranteed by one or more of its directly or indirectly wholly owned subsidiaries if indicated in the relevant prospectus supplement), guarantees of debt securities issued by Southwest Gas, depository shares, warrants to purchase common stock, preferred stock or depository shares issued by the Company or debt securities issued by the Company or Southwest Gas, units and rights. Additionally, as part of the Universal Shelf, Southwest Gas may offer and sell, from time to time in amounts at prices and on terms that will be determined at the time of such offering, any combination of debt securities (which may or may not be guaranteed by one or more of its directly or indirectly wholly owned subsidiaries if indicated in the relevant prospectus supplement) and guarantees of debt securities issued by the Company or by one or more of its directly or indirectly wholly owned subsidiaries, if indicated in the relevant prospectus supplement. The Universal Shelf is set to expire in November 2026. On August 6, 2024, the Company entered into an Equity Distribution Agreement with J.P. Morgan Securities LLC and Wells Fargo Securities, LLC for the offer and sale of up to 340,000,000 of common stock from time to time in an ATM Program. The offering amount was carried forward from the Company’s previous at-the-market equity offering program. The shares are issuable pursuant to the Company’s Universal Shelf. No issuances have occurred under the ATM Program as of December 31, 2025. During 2025, the Company issued approximately 186,000 shares of common stock through the omnibus incentive plan and restricted stock/unit plan. During 2025, the Company issued 256,000 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising proceeds of approximately $19.2 million. As of December 31, 2025, there were 5.0 million shares of common stock registered and available for issuance under the provisions of the various stock issuance plans.

Dispositions

12 Months Ended

Dec. 31, 2025

Dispositions

Note 13 - Dispositions

In December 2022, the Company announced that the Board unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest in an all-cash transaction to Williams for $1.5 billion in total enterprise value, subject to certain adjustments, which closed in the first quarter of 2023. Additionally, the Company determined it would pursue a separation of Centuri, including forming a new independent publicly traded utility infrastructure services company.

Centuri

In April 2024, the Company and Centuri announced the completion of the Centuri IPO, prior to which Centuri was a wholly owned subsidiary of the Company. Immediately upon the completion of the Centuri IPO, the Company continued to own approximately 81% of the outstanding shares of common stock of Centuri.

In May 2025, the Company completed a secondary public offering of 10,350,000 shares of Centuri’s common stock owned by the Company (inclusive of 1,350,000 shares related to the exercise of the overallotment option) at a price of $17.50 per share. In addition, the Company sold 2,857,142 shares at a price equal to the public offering price to the Icahn investment entities in a concurrent private placement. The net proceeds to the Company from this public offering and concurrent private placement, after deducting underwriting discounts and commissions of $6.6 million and other fees, were approximately $224.6 million.

In June 2025, the Company completed an additional secondary public offering of 11,212,500 shares of Centuri’s common stock owned by the Company (inclusive of 1,462,500 shares related to the exercise of the overallotment option) at a price of $20.75 per share. The net proceeds to the Company from the public offering, after deducting underwriting discounts and commissions of $8.6 million and other fees, were approximately $224.1 million. In addition, in July 2025 the Company closed the concurrent private placement sale of an additional 1,060,240 shares, at a price equal to the June 2025 Centuri public offering price, with Icahn investment entities. The net proceeds to the Company from this concurrent private placement were approximately $22.0 million. After completion of the June 2025 public offering and July 2025 private placement, the Company owned approximately 52.1% of the then-outstanding Centuri common stock.

On August 11, 2025, the Company completed an additional secondary public offering and concurrent private placement sale with Icahn investment entities for a combined total of 18,823,500 shares of Centuri common stock owned by the Company at a price of $19.50 per share. The net proceeds to the Company, after deducting underwriting discounts and commissions of $11.8 million and other fees, were approximately $355.2 million. The Company used the proceeds for the repayment of outstanding indebtedness, the third quarter dividends to stockholders, and will use the remainder for general corporate purposes (see Note 9 - Debt). After completion of the offering and concurrent private placement, the Company owned approximately 30.9% of the then-outstanding Centuri common stock, and therefore, no longer had a controlling financial interest in Centuri. As a result, the Company met the requirements for the deconsolidation of Centuri. In addition, the sale of Centuri, which comprised the Company’s Utility Infrastructure Services segment, represents a strategic shift that has a significant impact on the Company’s operations and financial results. Therefore, the sale meets the criteria to be reported as discontinued operations in accordance with U.S. GAAP. Accordingly, the historical financial results of Centuri, for all periods presented, are reflected in the Consolidated Financial Statements as discontinued operations. On August 11, 2025, following the deconsolidation of Centuri, the Company remeasured its retained 30.9% ownership interest at fair value. This remeasurement resulted in a gain of $222.9 million, which was included in the total gain recognized upon deconsolidation further described below. Subsequent to this date, the Company elected to continue measuring its retained interest, accounted for under the equity method, at fair value through the date of final disposition on September 5, 2025. Upon final disposition, the Company recognized a loss of $9.7 million. After considering the initial fair value adjustment, the Company recorded a net gain of $213.2 million related to the disposition on its retained interest in Centuri.

On September 5, 2025, the Company completed a final additional secondary public offering of 27,362,210 shares of Centuri common stock owned by the Company at a price of $19.18 per share. After completion of the offering, the Company no longer owns any shares of Centuri common stock and no longer has governance rights afforded to it under the Separation Agreement, including the right to nominate any of Centuri’s directors and any remaining consent rights over certain of Centuri’s corporate actions. The net proceeds to the Company from the public offering, after deducting other fees of approximately $900,000, were approximately $524.0 million.

Centuri did not receive any of the proceeds from the series of public offerings or private placements subsequent to the Centuri IPO. The Company used a portion of the proceeds to pay debts at Southwest Gas Holdings and expects to use the remaining proceeds for general corporate purposes, including support for future capital investments at Southwest Gas, as well as the 2028 expansion of Great Basin, and future dividend payments to stockholders that would otherwise have been funded by Southwest Gas.

The following table presents the net proceeds received by the Company for the sale of Centuri common stock subsequent to the Centuri IPO:


Secondary Offering Information	Net Proceeds (in million) (1)
May 22, 2025 public offering and private placement	$	224.6
June 18, 2025 public offering	224.1
July 8, 2025 private placement	22.0
August 11, 2025 public offering and private placement	355.2
September 5, 2025 public offering	524.0
Total	$	1,349.9

(1) Net proceeds, net of transaction costs

Discontinued Operations

The gain on deconsolidation as of August 11, 2025, adjusted during fourth quarter of 2025, is calculated as follows (in thousands):


Fair value of the retained investment in Centuri (1)	$	533,636
Net proceeds received from the August 11, 2025 public offering and private placement	355,220
Carrying value of noncontrolling interest attributable to Centuri prior to deconsolidation	460,897
Centuri deferred tax asset adjustment (2)	(24,257)
Less: Carrying value of Centuri net assets prior to deconsolidation, including AOCI	(982,396)
Gain on deconsolidation of Centuri before income tax (3)	343,100
Income tax expense	82,650
Gain on deconsolidation of Centuri, net of tax	$	260,450

(1) Centuri’s quoted stock price is used for fair value measurement, which is classified as level 1 in the fair value hierarchy as of August 11, 2025.

(3) Includes $120.2 million gain on interest sold and $222.9 million gain on the investment retained.

The following table summarizes the components of assets and liabilities of discontinued operations on the Company’s Condensed Consolidated Balance Sheets at December 31, 2024:


	December 31,
(Thousands of dollars)	2024
Cash	$	49,019
Accounts receivable, net of allowances	519,610
Other current assets	32,755
Total current assets classified as discontinued operations	601,384
Other property and investments, net	1,025,700
Goodwill	770,046
Deferred income taxes	52,376
Deferred charges and other assets	79,004
Total noncurrent assets classified as discontinued operations	1,927,126

Current maturities of long-term debt	30,018
Accounts payable	140,889

Other current liabilities	211,985
Total current liabilities classified as discontinued operations	382,892
Long-term debt, less current maturities	843,863

Other deferred credits	172,863
Total noncurrent liabilities classified as discontinued operations	$	1,016,726

Summarized results from discontinued operations were as follows:


(Thousands of dollars)	2025		2024		2023
Utility infrastructure services revenues	$	1,613,113	$	2,637,229	$	2,899,276
Utility infrastructure services expenses	(1,507,393)		(2,424,585)		(2,628,476)
Depreciation and amortization	(83,393)		(135,345)		(145,445)
Net interest deductions	(51,530)		(90,515)		(97,476)
Gain on deconsolidation	343,100		—		—
Loss on final disposition of retained interest	(9,688)		—		—
Other income (deductions), net	(135)		376		66
Income (loss) from discontinued operations before income taxes	304,074		(12,840)		27,945
Income tax expense	(103,730)		(3,303)		(12,422)
Net income (loss) from discontinued operations	200,344		(16,143)		15,523
Net income (loss) attributable to noncontrolling interest	(4,646)		6,021		4,628
Net income (loss) from discontinued operations attributable to Southwest Gas Holdings, Inc.	$	204,990	$	(22,164)	$	10,895

Following the May 2025 sale of Centuri common stock, the Company was no longer eligible to include Centuri in its consolidated federal and certain state income tax returns (tax deconsolidation) and the Company’s tax-free spin protection plan expired. As such, the Company could no longer assert the ability to complete a tax-free disposition of its investment in Centuri. This event required the Company to recognize a previously unrecorded deferred tax liability related to the outside basis of its investment in Centuri. As a result, the Company recognized tax expense of $52.8 million related to the recognition of outside basis differences. Following the sale of the Company’s shares of Centuri common stock in August 2025, the Company was no longer eligible to include Centuri in its remaining state income tax returns.

In addition, the Company recorded a tax benefit of $24.1 million related to deferred tax assets. These benefits reflect state net operating losses that are now expected to be utilized in connection with the disposition of Centuri shares.

As a result of the Centuri deconsolidation in August 2025, the Company recorded an income tax expense of $82.7 million. Furthermore, the Company recorded an income tax benefit of $5.6 million primarily related to the final disposition of Centuri, valuation allowance release, and for other separation costs. The Company also reflected a $2.0 million income tax benefit from the results of Centuri’s operations through the deconsolidation date resulting in a total income tax expense of $103.7 million.

On February 24, 2025, the Company entered into a Tax Assets Agreement with Centuri. The Tax Assets Agreement addresses the Company’s arrangements with Centuri with respect to certain Tax Assets that each company will retain following any deconsolidation for U.S. federal and relevant state income tax laws. Under the terms of the Tax Assets Agreement, the Company contributed $80.7 million, inclusive of the $24.3 million recording in the fourth quarter of 2025, of Tax Assets to Centuri, which were treated as a deemed capital contribution. This amount is subject to change and will be finalized upon the filing of the 2025 final consolidated or combined federal and state income tax returns. Any future changes to the Tax Assets contributed to Centuri will be recorded in discontinued operations.

The Company had $7.7 million of redeemable noncontrolling interests at December 31, 2024 that was disposed of in connection with the Centuri separation.

Receivables and Related Allowances (Tables)

12 Months Ended

Dec. 31, 2025

Receivables [Abstract]

Schedule of Accounts Receivable

The table below contains information about Southwest Gas’ gas utility customer accounts receivable balance (net of allowance) at December 31, 2025 and 2024:


	December 31,
(Thousands of dollars)	2025		2024
Gas utility customer accounts receivable balance	$	163,752	$	194,177

Schedule of Percent of Customers by State

The following table represents the percentage of customers in each of Southwest Gas’ three states at December 31, 2025, which was consistent with the prior year:


Percent of customers by state:
Arizona	54	%
Nevada	37	%
California	9	%

Schedule of Allowance for Uncollectibles

Southwest Gas activity in the allowance account for uncollectibles is summarized as follows:


(Thousands of dollars)	Allowance for Uncollectibles
Balance, December 31, 2022	$	4,830
Additions charged to expense	11,877
Accounts written off, less recoveries	(10,612)
Balance, December 31, 2023	6,095
Additions charged to expense	12,400
Accounts written off, less recoveries	(11,428)
Balance, December 31, 2024	7,067
Additions charged to expense	11,955
Accounts written off, less recoveries	(11,372)
Balance, December 31, 2025	$	7,650

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Regulated Operations Plant (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Net Utility Plant

Major classes of regulated operations plant and their respective balances as of December 31, 2025 and 2024 were as follows:


	December 31,
(Thousands of dollars)	2025		2024
Gas plant:
Storage	$	122,543	$	121,817
Transmission	461,260		447,719
Distribution	9,940,646		9,343,955
General	623,303		587,423
Software and software-related	354,567		328,769
Other	14,712		15,212
Total gas plant	11,517,031		10,844,895
Less: accumulated depreciation and amortization	(3,063,363)		(2,914,457)
Construction work in progress	236,871		178,647
Net regulated operations plant	$	8,690,539	$	8,109,085

Schedule of Depreciation and Amortization Expense

Depreciation and amortization expense on gas plant was as follows:


(Thousands of dollars)	2025		2024		2023
Depreciation and amortization expense	$	295,661	$	274,556	$	256,847

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2025
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations. This is a combined annual report of the Company and Southwest Gas. The combined notes to the consolidated financial statements apply to the Company and Southwest Gas unless otherwise described. Southwest Gas Holdings, a Delaware corporation, is a holding company owning all of the shares of common stock of Southwest Gas; until April 22, 2024, all of the shares of common stock of Centuri Holdings, Inc. (“Centuri”); and until February 14, 2023, all of the shares of common stock of MountainWest. The Company’s businesses were managed within three separate reportable segments until February 2023, our Natural Gas Distribution segment (Southwest Gas), our Utility Infrastructure Services segment (Centuri), and our Pipeline and Storage segment (MountainWest). After February 2023, the businesses were managed within two reportable segments, our Natural Gas Distribution segment (Southwest Gas) and our Utility Infrastructure Services segment (Centuri) until August 2025, After August 2025, our business is solely comprised of our Natural Gas Distribution segment (see Note 16 - Segment Information). Southwest Gas is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest Gas are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. While mechanisms exist in all states in which Southwest Gas operates which decouple authorized operating cost recovery and profitability from the volume of natural gas sold, thereby also incentivizing energy conservation, results for the Natural Gas Distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.
Basis of Presentation	Basis of Presentation. The Company follows U.S. GAAP in accounting for all of its businesses. Unless specified otherwise, all amounts are in U.S. dollars. Accounting for regulated operations conforms with U.S. GAAP as applied to rate-regulated companies and as prescribed by federal agencies and commissions of the various states in which the rate-regulated companies operate. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Certain items in the prior period financial statements have been reclassified to conform to the current year presentation. Such reclassifications did not affect revenue, operating income, net income, or total cash flows from operations, investing or financing activities. These include $74.3 million and $294.9 million of changes in accrued purchased gas costs, included in the changes in other current assets and liabilities, that were reclassified to changes in deferred purchased gas costs in the Company’s and Southwest’s consolidated statements of cash flows for the years ended December 31, 2024 and 2023, respectively. See Note 3 - Revision of Previously Issued Financial Statements for the discussion of the revision to the prior year financial statements. Discontinued Operations. On August 11, 2025, the Company completed a secondary public offering and a concurrent private placement transaction with Icahn investment entities. These transactions resulted in the sale of a combined total of 18,823,500 shares of Centuri common stock previously held by the Company (see Note 13 - Dispositions). Following the completion of these transactions, the Company no longer maintained a controlling financial interest in Centuri. Accordingly, Centuri’s assets, liabilities, and results of operations are no longer included in the Company’s consolidated financial statements. In addition, the sale of Centuri, which comprised the Company’s Utility Infrastructure Services segment, represented a strategic shift that had a significant impact on the Company’s operations and financial results. Therefore, Centuri met the criteria to be reported as discontinued operations in accordance with U.S. GAAP. The results of discontinued operations are aggregated and presented separately in the Consolidated Statements of Income and Consolidated Statements of Cash Flows for all periods presented. Assets and liabilities of the discontinued operations are aggregated and reported separately on the Consolidated Balance Sheets as of December 31, 2024. Unless otherwise noted, the financial disclosures and related information provided herein relate to our continuing operations, which exclude our former Utility Infrastructure Services segment, and we have recast prior period amounts to reflect discontinued operations.
Consolidation	Consolidation. The accompanying financial statements (as of and for the periods presented) are presented on a consolidated basis for the Company and Southwest Gas. All significant intercompany balances and transactions have been eliminated with the exception of transactions between Southwest Gas and Centuri in accordance with accounting treatment for rate-regulated entities.
Fair Value Measurements	Fair Value Measurements. Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows: Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date. Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly. Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The Company primarily used quoted market prices and other observable market pricing information (exclusive of any purchase accounting adjustments) in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and the postretirement benefits other than pensions required to be recorded and/or disclosed at fair value. The Company uses prices and inputs that are current as of the measurement date and recognizes transfers between levels at either the actual date of an event or a change in circumstance that caused the transfer.
Net Regulated Operations Plant	Net Regulated Operations Plant. Net regulated operations plant includes gas plant at original cost less the accumulated provision for depreciation and amortization plus any unamortized balance of acquisition adjustments. Original cost generally includes contracted services, material, payroll, and related costs such as taxes and certain benefits, general and administrative expenses applicable to construction efforts, and an allowance for funds used during construction less contributions in aid of construction.
Cash and Cash Equivalents	Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand, money market funds, and financial instruments with original maturities of three months or less. Such investments are carried at cost, which approximates fair value. Cash and cash equivalents of the Company include $250.5 million and $64.3 million of money market fund investments at December 31, 2025 and 2024, respectively. Of these amounts, $34.4 million and $48.8 million at December 31, 2025 and 2024, respectively, were held by Southwest Gas. The money market fund investments were acquired and are generally redeemable at their net asset value.
Income Taxes	Income Taxes. The asset and liability method of accounting is utilized for the recognition of income taxes. Under the asset and liability method, deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the years in which those temporary differences are anticipated to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in income tax rates is recognized in the period that includes the enactment date. For regulatory and financial reporting purposes, ITCs related to gas utility operations are deferred and amortized over the life of related fixed assets.
Deferred Purchased Gas Costs	Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable Southwest Gas to adjust billing rates for changes in the cost of natural gas purchased. The difference between the current cost of gas purchased and the cost of gas recovered in billed rates is deferred. Generally, these deferred amounts are recovered or refunded within one year.
Materials, supplies, and gas inventories	Materials, supplies, and gas inventories. Materials, supplies, and gas inventories for Southwest Gas and the Company includes gas pipe materials and operating supplies of $78.1 million and $77.8 million as of December 31, 2025 and 2024, respectively (carried at weighted average cost).
Prepaid and other current assets	Prepaid and other current assets. Prepaid and other current assets for Southwest Gas and the Company include, among other things, $91.1 million and $32.4 million related to a regulatory asset associated with the Arizona decoupling mechanism as of December 31, 2025 and 2024, respectively. Additionally, included in the balance for the Company is prepaid insurance premiums of $35.4 million and $25.3 million as of December 31, 2025 and 2024, respectively, and $33.9 million and $25.2 million as of December 31, 2025 and 2024, respectively, at Southwest Gas.
Goodwill	Goodwill. As required by U.S. GAAP, goodwill is assessed for impairment annually or more frequently if circumstances indicate impairment to the carrying value of goodwill may have occurred. The goodwill impairment analysis was conducted as of October 1, 2025 using a qualitative assessment, as permitted by U.S. GAAP. Management of the Company and Southwest Gas evaluated its reporting unit and operating segment and concluded that, following the sale of the of the Utility Infrastructure Services segment (Centuri), the Company operates solely within the Natural Gas Distribution segment (Southwest Gas);
Deferred charges and other assets	Deferred charges and other assets. Deferred charges and other assets for Southwest Gas and the Company include, among other things, cloud-based software of $33.9 million and $24.8 million as of December 31, 2025 and 2024, respectively, and a regulatory asset associated with pension for Arizona and Nevada of $246.4 million and $300.0 million as of December 31, 2025 and 2024, respectively. The change is due to the net actuarial gain
Noncontrolling Interest	Noncontrolling Interest. In connection with the Centuri IPO, the Company recorded a noncontrolling interest as part of equity in the Consolidated Balance Sheet (associated with the interests held by the new investors in Centuri) and recognized the excess of the fair value of the Centuri IPO proceeds over the carrying value of the noncontrolling interest, in addition to a portion of AOCI relevant to the proportional interest of the noncontrolling parties in Centuri, within Additional paid-in capital. The Consolidated Statements of Income include multiple components of comprehensive income attributable to noncontrolling interests following the Centuri IPO. These amounts, including those distinguishable from net income attributed to these parties, are separately presented in the Consolidated Statements of Equity. Following the completion of the Centuri Separation (see Note 13 - Dispositions below), the Company no longer maintained a controlling financial interest in Centuri. Accordingly, the noncontrolling interests in Centuri are no longer included in the Company’s consolidated financial statements.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interest. Separate from the noncontrolling ownership interest in Centuri, redeemable noncontrolling interests have been established in association with certain business acquisitions by Centuri. Following the completion of the Centuri Separation (see Note 13 - Dispositions below), the Company no longer maintained a controlling financial interest in Centuri. Accordingly, the redeemable noncontrolling interests in Centuri are no longer included in the Company’s consolidated financial statements.
Other Current Liabilities	Other Current Liabilities. Management recognizes in its balance sheets various liabilities that are expected to be settled through future cash payments within the next twelve months, including certain regulatory mechanisms (refer to Note 5 - Regulatory Assets and Liabilities), customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities.
Accumulated Removal Costs	Accumulated Removal Costs. Approved regulatory practices allow Southwest Gas to include in depreciation expense a component intended to recover removal costs associated with regulated operations plant retirements. In accordance with the SEC position on presentation of these amounts, management reclassifies estimated removal costs from Accumulated depreciation to Accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Management regularly updates the estimated accumulated removal costs as amounts fluctuate between periods depending on the level of replacement work performed (and actual cost experience) compared to the estimated cost of removal in rates.
Revenue	Revenue. See Note 6 - Revenue for information related to revenue recognition for Southwest Gas. Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest Gas (see Note 16 - Segment Information). The accounts receivable balance, revenues, and associated profits were included in the consolidated financial statements of the Company and Southwest Gas and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities through the period prior to deconsolidation (see Note 13 - Dispositions). Net Cost of Gas Sold. Components of net cost of gas sold include natural gas commodity costs (fixed-price and variable-rate), pipeline capacity/transportation costs, and any actual settled costs of natural gas derivative instruments, where relevant. Also included are the net impacts of PGA deferrals and recoveries which by their inclusion result in net cost of gas sold overall that is comparable to amounts included in billed gas operating revenues. Differences between amounts incurred with suppliers, transmission pipelines, etc. and amounts already included in customer rates are temporarily deferred in PGA accounts pending inclusion in customer rates.
Operations and Maintenance Expense	Operations and Maintenance Expense. Operations and maintenance expense includes, Southwest Gas’ operating and maintenance costs associated with serving utility customers and maintaining its distribution and transmission systems, uncollectible customer accounts expense, administrative and general salaries and expense, and employee benefits expense excluding relevant non-service cost components (that have been reclassified to Other income (deductions) due to requirements in U.S. GAAP), as well as legal expenses (including injuries and damages), professional and other external contracted services, and other business expenses.
Depreciation and Amortization	Depreciation and Amortization. Regulated operations plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which compensate for removal costs (net of salvage value), and retirements, as approved by the appropriate regulatory agency. When plant is retired from service, the original cost of plant, including cost of removal, less salvage, is charged to the accumulated provision for depreciation. See also discussion regarding Accumulated Removal Costs above. Other regulatory assets, including acquisition adjustments, are amortized, when appropriate, over time periods authorized by regulators. Costs and gains related to refunding regulated operations debt and debt issuance expenses are deferred and amortized over the weighted-average lives of the new issues and become a component of interest expense.
Allowance for Funds Used During Construction ("AFUDC")	AFUDC. AFUDC represents the cost of both debt and equity funds used to finance regulated operations plant construction. AFUDC is capitalized as part of the cost of regulated operations plant. The debt portion of AFUDC is reported in the Company’s and Southwest Gas’ Consolidated Statements of Income as an offset to Net interest deductions and the equity portion is reported as Other income.
Derivatives	Derivatives. In managing its natural gas supply portfolios, Southwest Gas has historically entered into fixed- and variable-price contracts, which qualify as derivatives. The fixed-price contracts, firm commitments to purchase a fixed amount of gas in the future at a fixed price, qualify for the normal purchases and normal sales exception that is allowed for contracts that are probable of delivery in the normal course of business and are exempt from fair value reporting. The variable‑price contracts meet the definition of derivative financial instruments; however, because the contract price is set at the prevailing market price on the future transaction date, no mark‑to‑market adjustment is required. Southwest Gas does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations.
Earnings Per Share	EPS. Basic EPS in each period of this report were calculated by dividing net income (loss) attributable to the Company by the weighted-average number of shares during those periods. Diluted EPS includes additional weighted-average common stock equivalents (performance share units and restricted stock units), if dilutive. Unless otherwise noted, the term EPS refers to Basic EPS.
Recent Accounting Standards Updates	Recent Accounting Standards Updates. Recently issued accounting pronouncement adopted in 2025: In December 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” The update, among other amendments, provides for additional disclosure requirements related to the effective income tax rate reconciliation and income taxes paid. Under the revised guidance for the effective income tax reconciliations, entities would be required to disclose: (1) eight specific categories in the effective income tax rate reconciliation in both percentages and reporting currency amount, (2) additional information for reconciling items over a certain threshold, (3) explanation of individual reconciling items disclosed, and (4) provide a qualitative description of the state and local jurisdictions that contribute to the majority of the state income tax expense. For each annual period presented, the new standard requires disclosure of the year-to-date amount of income taxes paid (net of refunds received) disaggregated by federal, state, and foreign. It also requires additional disaggregated information on income taxes paid (net of refunds received) to an individual jurisdiction equal to or greater than 5% of total income taxes paid (net of refunds received). The standard is effective for annual periods beginning January 1, 2025. The Company and Southwest Gas have retrospectively adopted this update in the fourth quarter of 2025, the impact of which is reflected in Note 11 - Income Taxes, with no impact on results of operations, cash flows, or financial condition of the Company or Southwest Gas. In July 2025, the FASB issued ASU 2025-05 “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets.” The amendments in this update provide a practical expedient permitting an entity to assume that conditions at the balance sheet date remain unchanged over the life of the asset when estimating expected credit losses for current accounts receivable and current contract assets. The update is effective for annual periods beginning after December 15, 2025; early adoption is permitted. Management adopted ASU 2025-05 beginning with the fourth quarter of fiscal 2025 and utilized the practical expedient provided therein. The adoption of this ASU did not have a material impact on the Company’s or Southwest Gas’ financial position or results of operations. Recently issued accounting pronouncements that will be effective in 2026 and thereafter: In November 2024, the FASB issued ASU 2024-03 “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” The update requires disclosure of disaggregated information about certain income statement expense line items in the notes to the financial statements. The update is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027; early adoption is permitted. The update should be applied prospectively; however, retrospective application is also permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest Gas’ disclosures. In September 2025, the FASB issued ASU 2025-06 “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software.” The amendments in this update improve the operability of the guidance by removing all references to software development project stages so that the guidance is neutral to different software development methods. This update is effective for annual periods beginning after December 15, 2027, including interim periods within those fiscal years; early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest Gas’ consolidated financial statements.
Subsequent Events	Subsequent Events. Management monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made and has reflected them where appropriate.
Receivables and Related Allowances	Business activity with respect to natural gas utility operations is conducted with customers located within the three-state region of Arizona, Nevada, and California. Southwest Gas’ accounts receivable are short-term in nature with billing due dates customarily not extending beyond one month. Customers’ credit worthiness is assessed upon account creation by evaluation of other utility service or their credit file and related payment history. Although Southwest Gas seeks to minimize its credit risk related to utility operations by requiring security deposits from new customers, imposing late fees, and actively pursuing collection on overdue accounts where possible, some accounts are ultimately not collected. Customer accounts are subject to collection procedures that vary by jurisdiction, such as late fee assessment, notice requirements for disconnection of service, and procedures for actual disconnection and/or reestablishment of service. After disconnection of service, accounts are customarily written off approximately two months after disconnection if the account remains inactive. Depending upon the jurisdiction, reestablishment of service requires both the payment of previously unpaid balances and additional deposit requirements. Generally, costs related to uncollectible accounts are included in the ratemaking process as a cost of service. However, the Nevada and California jurisdictions have certain regulatory mechanisms in place to separately track and collect portions of uncollectible accounts through the mechanisms. Eligible amounts are deferred and collected through a surcharge in the ratemaking process. Southwest Gas continues to actively work with customers experiencing financial hardship by means of flexible payment options and partnering with assistance agencies. Provisions for uncollectible accounts are recorded monthly based on each customer’s current ability to pay amounts that are due, payment history, consideration of current conditions, customer and rate composition, regulatory requirements, and write-off processes.

Previously Issued Condensed Consolidated Financial Statements (Unaudited) - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 260,117	$ (37,600)		$ 71,587	$ 331,704	$ 435,180	$ 204,836	$ 155,517
Comprehensive income (loss)	258,724	(30,622)		78,937	337,661	444,188	196,860	155,972
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	262,037	(34,241)		79,981	342,018	448,545	192,180	151,344
Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	6,343	45,646	$ 142,595	188,241	194,584	300,308	262,096	228,412
Comprehensive income (loss)	6,612	45,913	142,863	188,776	195,388	$ 304,163	264,243	226,125
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	267,959	(10,329)		98,858	366,817
Comprehensive income (loss)	266,566	(3,351)		106,208	372,774
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	269,879	(6,970)		107,252	377,131
As Reported \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	5,520	33,677	142,942	176,619	182,139		261,176	242,226
Comprehensive income (loss)	5,789	33,944	143,210	177,154	182,943		263,323	239,939
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Comprehensive income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	(7,842)	(27,271)		(27,271)	(35,113)
Adjustments \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	823	11,969	(347)	11,622	12,445		920	(13,814)
Comprehensive income (loss)	$ 823	$ 11,969	$ (347)	$ 11,622	$ 12,445		$ 920	$ (13,814)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
Cybersecurity Risk Management and Strategy Disclosure	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	We recognize the importance of assessing, identifying, and managing material risks associated with cybersecurity threats. These risks include, among other things: operational risks, intellectual property and proprietary business information theft, fraud, extortion, harm to employees or customers, violation of privacy or security laws and other litigation and legal risk, physical damage to utility and transmission infrastructure, and reputational harm. We have implemented cybersecurity processes, technologies, and controls to aid in our efforts to assess, identify, and manage these risks. As part of our enterprise risk management program, we consider cybersecurity risks alongside other risks in our overall risk assessment process. Our enterprise risk professionals collaborate with subject matter specialists, as necessary, to gather insights for identifying material cybersecurity threats, assessing their severity, and deploying potential mitigation strategies. Southwest Gas’ cybersecurity program focuses on people, processes, and technology, and takes a defense-in-depth approach by seeking to align with industry best practices. We employ ongoing cybersecurity awareness training and testing for employees, by means of which we teach employees about remaining vigilant in daily work activities and practicing good security awareness. Specialized cybersecurity training is provided to those in specific job functions particularly susceptible to cyber incidents and phishing simulations are conducted monthly. Annually, a cybersecurity fair is held, and every employee is encouraged to participate. During this fair, outside experts present current and relevant information in an engaging and educational atmosphere. Tabletop exercises are periodically conducted to evaluate controls, processes, and procedures within Southwest Gas, and with our partners, in the handling of a cybersecurity incident. Southwest Gas maintains partnerships with law enforcement and other participants within the natural gas and electric utility industries. We also participate in the Information Sharing and Analysis Center to share threat intelligence and collaborate on cybersecurity issues affecting our industry. As a natural gas LDC, Southwest Gas’ objective is to comply with the TSA security directives for our gas monitoring and control systems. Pursuant to these directives, Southwest Gas engages outside consultants to regularly review our technical architecture and alignment with the TSA security directives. In addition to complying with these regulations, Southwest Gas takes a risk-based approach to identify areas for future cybersecurity investment and periodically engages experts to attempt to infiltrate our information systems to further strengthen our security posture. We invest in a range of cybersecurity technologies within the perimeter, network, and endpoints; creating a defense-in-depth architecture designed for prevention and response to cybersecurity events and to help minimize risk exposure. To provide for the availability of critical data and systems, maintain regulatory compliance, manage our risks from cybersecurity threats, and to protect against, detect, and respond to cybersecurity incidents, Southwest Gas undertakes the following activities: •deploys a defense-in-depth approach with security measures in place at multiple layers; •closely monitors information systems using a suite of technologies and a specialized cybersecurity team; •reviews emerging data protection laws and implements changes to our processes designed for compliance; •avoids, where possible, the storage on our information systems of sensitive customer information, such as social security numbers or banking information, where practicable; •conducts regular phishing email simulations for employees and contractors with access to corporate email systems to enhance awareness and responsiveness to possible threats; •through policy, practice, and contracts (as applicable), encourages employees, as well as third parties who provide services on our behalf, to treat customer information and data with care; •runs tabletop exercises to simulate response activities to a cybersecurity incident and use the findings to improve our processes and technologies; •leverages the National Institute of Standards and Technology (“NIST”) Computer Security Incident Handling Process as a guideline to help identify, protect, detect, respond, and recover when there is an actual or potential cybersecurity incident; and •conducts vulnerability and penetration assessments, with associated remediation activities. Southwest Gas’ incident response plan is designed to coordinate the activities we take to prepare for, detect, respond to, and recover from cybersecurity incidents. These activities include processes to triage, assess severity, communicate, contain, investigate, and remediate the incident, as well as to comply with applicable legal obligations and mitigate reputational damage. Southwest Gas’ processes also address cybersecurity threat risks associated with our use of third-party service providers, including those in our supply chain or those who have access to customer and employee data or our systems. Third-party risks are included within our cybersecurity-specific risk identification program. In addition, cybersecurity considerations affect the selection and oversight of our third-party service providers. We perform diligence on third parties that have access to our systems, data, or facilities that house such systems or data, and monitor cybersecurity threat risks identified through our diligence review. Our due diligence process involves the use of technology-enabled assessments of the third-party’s cybersecurity posture, which are reviewed by both business representatives and cybersecurity specialists. We use the results of the assessments to assist in finding ways to mitigate risks presented by a particular third-party service provider, consistent with the services provided. Additionally, contracts with third parties that could introduce significant cybersecurity risk to Southwest Gas include terms to assist in the mitigation of cybersecurity risks, including but not limited to, requiring counterparties to report data privacy or cybersecurity incidents to us and where appropriate, other risk-mitigation measures. We describe whether and how risks from identified cybersecurity threats, including as a result of any previous cybersecurity incidents, have materially affected or are reasonably likely to materially affect us, including our business strategy, results of operations, or financial condition, under the heading “Operational Risks” as part of our risk factor disclosures in Item 1A of this Annual Report on Form 10-K, which are incorporated by reference herein. In the last three fiscal years, we have not experienced any material cybersecurity incidents and the expenses we have incurred from cybersecurity incidents were immaterial. However, because Southwest Gas’ operations involve critical infrastructure, as defined under federal law and by the TSA, we have been and will continue to be the target of cybersecurity attacks from time to time.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	These risks include, among other things: operational risks, intellectual property and proprietary business information theft, fraud, extortion, harm to employees or customers, violation of privacy or security laws and other litigation and legal risk, physical damage to utility and transmission infrastructure, and reputational harm. We have implemented cybersecurity processes, technologies, and controls to aid in our efforts to assess, identify, and manage these risks. As part of our enterprise risk management program, we consider cybersecurity risks alongside other risks in our overall risk assessment process. Our enterprise risk professionals collaborate with subject matter specialists, as necessary, to gather insights for identifying material cybersecurity threats, assessing their severity, and deploying potential mitigation strategies. Southwest Gas’ cybersecurity program focuses on people, processes, and technology, and takes a defense-in-depth approach by seeking to align with industry best practices. We employ ongoing cybersecurity awareness training and testing for employees, by means of which we teach employees about remaining vigilant in daily work activities and practicing good security awareness. Specialized cybersecurity training is provided to those in specific job functions particularly susceptible to cyber incidents and phishing simulations are conducted monthly. Annually, a cybersecurity fair is held, and every employee is encouraged to participate. During this fair, outside experts present current and relevant information in an engaging and educational atmosphere. Tabletop exercises are periodically conducted to evaluate controls, processes, and procedures within Southwest Gas, and with our partners, in the handling of a cybersecurity incident. Southwest Gas maintains partnerships with law enforcement and other participants within the natural gas and electric utility industries. We also participate in the Information Sharing and Analysis Center to share threat intelligence and collaborate on cybersecurity issues affecting our industry.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Cybersecurity is an important part of our risk management processes and an area of increasing focus for our Board and management. The responsibility for oversight of risks from cybersecurity threats rests with our entire Board, but the Audit Committee oversees certain cybersecurity related items as described below.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	The responsibility for oversight of risks from cybersecurity threats rests with our entire Board, but the Audit Committee oversees certain cybersecurity related items as described below. At least twice per year the entire Board receives an overview from management on our cybersecurity threat risk management and strategy processes covering topics such as data security posture, results from third-party assessments, and cybersecurity threat risks or incidents and developments, as well as the steps management took to respond to such risks. Additionally, our Chief Information Officer attends Audit Committee meetings to present cybersecurity information for consideration in financial reporting, as necessary, and attends private Executive Sessions with the Audit Committee. Our Director of Internal Audit reports to the Audit Committee regarding attack and penetration exercise results and remediation. Members of the Board are also encouraged to regularly engage in ad hoc conversations with management on cybersecurity-related news or events and discuss any significant updates to our cybersecurity risk management and strategy programs. Material cybersecurity threat risks are also considered during separate Board meeting discussions of matters such as enterprise risk management, operational budgeting, mergers and acquisitions, and other relevant matters.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	At least twice per year the entire Board receives an overview from management on our cybersecurity threat risk management and strategy processes covering topics such as data security posture, results from third-party assessments, and cybersecurity threat risks or incidents and developments, as well as the steps management took to respond to such risks. Additionally, our Chief Information Officer attends Audit Committee meetings to present cybersecurity information for consideration in financial reporting, as necessary, and attends private Executive Sessions with the Audit Committee. Our Director of Internal Audit reports to the Audit Committee regarding attack and penetration exercise results and remediation. Members of the Board are also encouraged to regularly engage in ad hoc conversations with management on cybersecurity-related news or events and discuss any significant updates to our cybersecurity risk management and strategy programs. Material cybersecurity threat risks are also considered during separate Board meeting discussions of matters such as enterprise risk management, operational budgeting, mergers and acquisitions, and other relevant matters.
Cybersecurity Risk Role of Management [Text Block]	Cybersecurity is an important part of our risk management processes and an area of increasing focus for our Board and management. The responsibility for oversight of risks from cybersecurity threats rests with our entire Board, but the Audit Committee oversees certain cybersecurity related items as described below. At least twice per year the entire Board receives an overview from management on our cybersecurity threat risk management and strategy processes covering topics such as data security posture, results from third-party assessments, and cybersecurity threat risks or incidents and developments, as well as the steps management took to respond to such risks. Additionally, our Chief Information Officer attends Audit Committee meetings to present cybersecurity information for consideration in financial reporting, as necessary, and attends private Executive Sessions with the Audit Committee. Our Director of Internal Audit reports to the Audit Committee regarding attack and penetration exercise results and remediation. Members of the Board are also encouraged to regularly engage in ad hoc conversations with management on cybersecurity-related news or events and discuss any significant updates to our cybersecurity risk management and strategy programs. Material cybersecurity threat risks are also considered during separate Board meeting discussions of matters such as enterprise risk management, operational budgeting, mergers and acquisitions, and other relevant matters. At the management level for Southwest Gas, our cybersecurity risk management and strategy processes, which are discussed in greater detail above, are led by Southwest Gas’ President and the Vice President/Information Services/Chief Information Officer, along with the Director of Information Security. A Cybersecurity Executive Committee, consisting of officer-level management appointees representing key areas of our business, exists to maintain situational awareness of cybersecurity risks, support methods of addressing cybersecurity risks, and support the Chief Information Officer’s efforts to help Southwest Gas follow natural gas sector-specific regulations and reporting. The Cybersecurity Executive Committee meets regularly with legal advisors and cybersecurity professionals. In our Information Services department, the cybersecurity management team members hold relevant degrees and industry-recognized certifications in cybersecurity, and each has many years of relevant work experience in various roles involving managing information security, developing cybersecurity strategy, and implementing effective information and cybersecurity programs. Cybersecurity team members are expected to keep their knowledge, skills, and training current by participating in industry events and continuing education programs as applicable. These members of management are informed about and monitor the prevention, mitigation, detection, and remediation of cybersecurity incidents through their management of, and participation in, the cybersecurity risk management and strategy processes described above, including the operation of our incident response plan. Our cybersecurity playbooks and incident response plan outline our procedures, communication protocols, and information escalation processes applicable throughout the lifecycle of a cybersecurity incident. The playbooks and plans cover information flow from discovery of a possible issue through the reporting of it to Information Services management, legal counsel, executive management, and Board as necessary. As discussed above, members of management report to the entire Board about cybersecurity threat risks, among other cybersecurity related matters, at least twice per year, with the Audit Committee receiving more frequent updates as needed to assist in maintaining or enhancing cybersecurity posture in financial reporting and monitoring attack and penetration testing results.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	A Cybersecurity Executive Committee, consisting of officer-level management appointees representing key areas of our business, exists to maintain situational awareness of cybersecurity risks, support methods of addressing cybersecurity risks, and support the Chief Information Officer’s efforts to help Southwest Gas follow natural gas sector-specific regulations and reporting. The Cybersecurity Executive Committee meets regularly with legal advisors and cybersecurity professionals. In our Information Services department, the cybersecurity management team members hold relevant degrees and industry-recognized certifications in cybersecurity, and each has many years of relevant work experience in various roles involving managing information security, developing cybersecurity strategy, and implementing effective information and cybersecurity programs. Cybersecurity team members are expected to keep their knowledge, skills, and training current by participating in industry events and continuing education programs as applicable.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	In our Information Services department, the cybersecurity management team members hold relevant degrees and industry-recognized certifications in cybersecurity, and each has many years of relevant work experience in various roles involving managing information security, developing cybersecurity strategy, and implementing effective information and cybersecurity programs. Cybersecurity team members are expected to keep their knowledge, skills, and training current by participating in industry events and continuing education programs as applicable.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	These members of management are informed about and monitor the prevention, mitigation, detection, and remediation of cybersecurity incidents through their management of, and participation in, the cybersecurity risk management and strategy processes described above, including the operation of our incident response plan. Our cybersecurity playbooks and incident response plan outline our procedures, communication protocols, and information escalation processes applicable throughout the lifecycle of a cybersecurity incident. The playbooks and plans cover information flow from discovery of a possible issue through the reporting of it to Information Services management, legal counsel, executive management, and Board as necessary.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Debt - Schedule of Estimated Maturities of Long-Term Debt (Details) $ in Thousands	Dec. 31, 2025 USD ($)
Debt Instrument [Line Items]
2026	$ 75,000
2027	332,500
2028	650,000
2029	0
2030	450,000
Debentures
Debt Instrument [Line Items]
2026	75,000
2027	332,500
2028	650,000
2029	0
2030	$ 450,000

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Beginning balance (in shares) at Dec. 31, 2022

CONSOLIDATED STATEMENTS OF EQUITY - USD ($)
$ in Thousands

Total

Southwest Gas Holdings, Inc.

Common stock shares

Additional Paid-in Capital

AOCI

Retained Earnings

Noncontrolling Interest

67,119,000

Beginning balance at Dec. 31, 2022

$ 3,058,759

$ 68,749

$ 2,287,183

$ (44,242)

$ 747,069

$ 0

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Common stock issuances (in shares)

150,889

4,445,000

Common stock issuances

259,002

$ 4,445

254,557

Dividends declared ($2.48 per share)

(178,485)

Promissory notes in association with redeemable noncontrolling interest

Foreign currency exchange translation adjustment

2,742

Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax

(2,287)

Redemption value adjustments

19,366

Ending balance (in shares) at Dec. 31, 2023

71,564,000

Ending balance at Dec. 31, 2023

3,310,036

$ 73,194

2,541,790

(43,787)

738,839

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Common stock issuances (in shares)

198,815

6,119

219,000

Common stock issuances

21,579

$ 219

21,360

Dividends declared ($2.48 per share)

(178,811)

Promissory notes in association with redeemable noncontrolling interest

4,187

Centuri IPO

327,667

155,210

154,006

1,204

172,457

Foreign currency exchange translation adjustment

(10,123)

(8,782)

(1,341)

Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax

$ 2,147

2,147

Redemption value adjustments

(194)

Ending balance (in shares) at Dec. 31, 2024

71,782,756

71,783,000

Ending balance at Dec. 31, 2024

$ 3,681,422

3,504,187

$ 73,413

2,721,343

(49,218)

758,649

177,235

Beginning balance (in shares) at Dec. 31, 2024

71,782,756

71,783,000

Beginning balance at Dec. 31, 2024

$ 3,681,422

3,504,187

$ 73,413

2,721,343

(49,218)

758,649

177,235

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Common stock issuances (in shares)

439,826

(4,694)

441,000

Common stock issuances

37,276

$ 441

36,835

Dividends declared ($2.48 per share)

(179,845)

Centuri stock sales and other

^[1]

426,070

146,601

140,787

1,598

4,216

279,469

Centuri deconsolidation

(447,944)

4,355

(452,299)

Foreign currency exchange translation adjustment

5,153

4,864

289

Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax

$ 3,855

3,855

Ending balance (in shares) at Dec. 31, 2025

72,224,593

72,224,000

Ending balance at Dec. 31, 2025

$ 3,961,119

3,961,119

$ 73,854

$ 2,898,965

$ (34,546)

1,022,846

$ 0

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Ending balance at Jun. 30, 2025

(40,154)

4,088,534

3,647,386

742,452

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Ending balance at Sep. 30, 2025

262,634

$ 3,893,566

$ 964,286

[1]	(1) Includes the impact of the contributed Tax Assets - see Note 13 - Dispositions.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 15 - Commitments and Contingencies The Company and Southwest Gas are defendants in miscellaneous legal proceedings. They are also parties to various regulatory proceedings. The ultimate dispositions of these proceedings are not presently determinable; however, it is the opinion of management that no litigation or regulatory proceedings to which the Company and Southwest Gas are currently subject will have a material adverse impact on their financial position, results of operations, or cash flows. The Company maintains excess liability insurance that covers Southwest Gas for various risks associated with the operation of the natural gas pipelines and facilities. In connection with these liability insurance policies, Southwest Gas is responsible for an initial deductible or self-insured retention amount per incident after which the insurance carriers would be responsible for amounts up to the policy limits. For the policy period of August 2025 to July 2026, these liability insurance policies require Southwest Gas, as applicable, to be responsible for the first $1.0 million (self-insured retention) of each incident plus a supplemental retention aggregate of $4.0 million in the policy year. When amounts are expected to be incurred above these amounts, subject to insurance carrier indemnity, a liability is recognized for the additional amount, in addition to a receivable, associated with amounts expected to be indemnified by the insurance carrier amounts, without impact to earnings. Through an assessment process of commitments and contingencies of any kind, the Company and Southwest Gas may determine that certain costs are likely to be incurred in the future related to specific legal matters. In these circumstances and in accordance with accounting policies, the Company and Southwest Gas will make an accrual, as necessary.

Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Regulatory Assets

The following table represents existing regulatory assets and liabilities. The amounts reported in the table below differ from Southwest Gas due to the revision Note 3 - Revision of Previously Issued Financial Statements.


	December 31,
(Thousands of dollars)	2025		2024
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	246,444	$	299,961
Deferred purchased gas costs (2)	5,214		13,807
Unamortized premium on reacquired debt (3)	10,016		11,529
Accrued absence time (4)	22,430		21,231
Margin, interest- and property tax-tracking (5)	142,813		57,477
Other (9)	92,820		90,083
Total regulatory assets	$	519,737	$	494,088
Regulatory liabilities:
Deferred purchased gas costs (2),(10)	(310,085)		(255,398)
Accumulated removal costs (6)	(496,000)		(472,000)
Unamortized gain on reacquired debt (7)	(4,963)		(5,500)
Regulatory excess deferred/other taxes and gross-up (8)	(348,243)		(363,353)
Margin, interest- and property tax-tracking (5)	(26,019)		(25,112)
Other (9)	(10,374)		(3,465)
Total regulatory liabilities	(1,195,684)		(1,124,828)
Net regulatory assets (liabilities) (11)	$	(675,947)	$	(630,740)

(1) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 10 - Pension and Other Postretirement Benefits).

(2) Balance recovered or refunded on an ongoing basis with interest.

(3) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(4) Recovery through cost of service generally on a one-year lag basis and part of overhead loading processes. Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(5) Margin tracking/decoupling mechanisms are alternative revenue programs; revenue associated with under-collections (for the difference between authorized margin levels and amounts billed to customers through rates currently) is recognized as revenue so long as recovery is expected to take place within 24 months. The property tax tracking mechanism reflects differences in property tax expense and the amount included in the current general rate case. Total category asset balances are included in Prepaid and other current assets and Deferred charges and other assets on the Consolidated Balance Sheets. For 2025, total category liability balances are included in Other deferred credits and other long-term liabilities. For 2024, total category liability balances are included in Other current liabilities and Other deferred credits and other long-term liabilities.

(6) Included in Accumulated removal costs on the Consolidated Balance Sheets; a component of ongoing depreciation rates as part of margin rates overall and of benchmarks under trackers as part of general rate cases.

(7) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets; amortized over life of debt instruments.

(8) Includes remeasurement/reduction of the net accumulated deferred income tax liability from U.S. tax reform. The reduction (EADIT) became a regulatory liability with tax gross-up. EADIT reduces rate base, and is expected to be returned to utility customers in accordance with IRS and regulatory requirements. Included generally in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets, except for $10.0 million in 2025 and $21.0 million in 2024, which is in Other current liabilities.

(9) The following tables detail the components of Other regulatory assets and liabilities. Other regulatory assets are included in either Prepaid and other current assets or Deferred charges and other assets on the Consolidated Balance Sheets (as indicated). Recovery periods vary. Other regulatory liabilities are included in either Other current liabilities or Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets (as indicated).

(10) Deferred purchased gas costs as of December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(11) Net regulatory assets (liabilities) for the year ended December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (f)	$	21,308	$	24,404
Infrastructure replacement programs and similar (b) (f)	32,516		24,262
Environmental compliance programs (c) (f)	7,087		3,730
Pension tracking mechanism (d)	16,727		16,151
Other (e)	15,182		21,536
	$	92,820	$	90,083

(a) Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(b) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(c) In 2025, approximately $5.5 million of these balances included in Prepaid and other current assets and $1.6 million in Deferred charges and other assets on the Consolidated Balance Sheets. In 2024, approximately $2.6 million included in Prepaid and other current assets and $1.1 million included in Deferred charges and other assets on the Consolidated Balance Sheets.

(d) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(e) In 2025, approximately $7.6 million included in Prepaid and other current assets and $7.6 million included in Deferred charges and other assets on the Consolidated Balance Sheets. In 2024, $11.7 million included in Prepaid and other current assets and $9.9 million included in Deferred charges and other assets on the Consolidated Balance Sheets.

(f) Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Liabilities:

Infrastructure replacement programs and similar (g)	$	(2,484)	$	(2,069)
Environmental compliance programs (g) (h)	(6,710)		(733)

Other (h) (i)	(1,180)		(663)
	$	(10,374)	$	(3,465)

(g) Included in Other current liabilities on the Consolidated Balance Sheets.

(h) Balance typically recovered or refunded on an ongoing basis, generally with interest.

(i) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

Schedule of Regulatory Liabilities


	December 31,
(Thousands of dollars)	2025		2024
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	246,444	$	299,961
Deferred purchased gas costs (2)	5,214		13,807
Unamortized premium on reacquired debt (3)	10,016		11,529
Accrued absence time (4)	22,430		21,231
Margin, interest- and property tax-tracking (5)	142,813		57,477
Other (9)	92,820		90,083
Total regulatory assets	$	519,737	$	494,088
Regulatory liabilities:
Deferred purchased gas costs (2),(10)	(310,085)		(255,398)
Accumulated removal costs (6)	(496,000)		(472,000)
Unamortized gain on reacquired debt (7)	(4,963)		(5,500)
Regulatory excess deferred/other taxes and gross-up (8)	(348,243)		(363,353)
Margin, interest- and property tax-tracking (5)	(26,019)		(25,112)
Other (9)	(10,374)		(3,465)
Total regulatory liabilities	(1,195,684)		(1,124,828)
Net regulatory assets (liabilities) (11)	$	(675,947)	$	(630,740)

(1) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 10 - Pension and Other Postretirement Benefits).

(2) Balance recovered or refunded on an ongoing basis with interest.

(3) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(4) Recovery through cost of service generally on a one-year lag basis and part of overhead loading processes. Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(7) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets; amortized over life of debt instruments.

(10) Deferred purchased gas costs as of December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(11) Net regulatory assets (liabilities) for the year ended December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (f)	$	21,308	$	24,404
Infrastructure replacement programs and similar (b) (f)	32,516		24,262
Environmental compliance programs (c) (f)	7,087		3,730
Pension tracking mechanism (d)	16,727		16,151
Other (e)	15,182		21,536
	$	92,820	$	90,083

(a) Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(b) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(d) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(f) Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Liabilities:

Infrastructure replacement programs and similar (g)	$	(2,484)	$	(2,069)
Environmental compliance programs (g) (h)	(6,710)		(733)

Other (h) (i)	(1,180)		(663)
	$	(10,374)	$	(3,465)

(g) Included in Other current liabilities on the Consolidated Balance Sheets.

(h) Balance typically recovered or refunded on an ongoing basis, generally with interest.

(i) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of Income Before Taxes

The following is a summary of income before taxes from continuing operations:


	Year ended December 31,
(Thousands of dollars)	2025		2024		2023
Income from continuing operations before income taxes	$	330,873	$	254,136	$	169,404

The following is a summary of income before taxes:


	Year ended December 31,
(Thousands of dollars)	2025		2024		2023
Total income before income taxes	$	353,131	$	304,765	$	270,574

Schedule of Income Tax Expense (Benefit)

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Current:
Federal	$	(24)	$	1,289	$	(66)
State	1,777		570		402
Total current tax expense	1,753		1,859		336
Deferred:
Federal	55,547		28,627		19,400
State	38,737		2,671		9,674
Total deferred tax expense	94,284		31,298		29,074
Total income tax expense	$	96,037	$	33,157	$	29,410

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Current:
Federal	$	(96,017)	$	(12)	$	(21)
State	(9,051)		105		98
Total current tax expense	(105,068)		93		77
Deferred:
Federal	156,138		39,730		30,980
State	1,753		2,846		11,105
Total deferred tax expense	157,891		42,576		42,085
Total income tax expense	$	52,823	$	42,669	$	42,162

Schedule of Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate

A reconciliation of the U.S. federal statutory rate to the Southwest Gas Holdings, Inc. consolidated effective income tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2025				2024				2023
(Thousands of dollars)	Amount		Percent		Amount		Percent		Amount		Percent
U.S. federal statutory income tax	$	69,483	21.0	%	$	53,369	21.0	%	$	35,575	21.0	%
State and local income tax, net of deferred benefit (1)	40,515		12.2	%	3,230		1.2	%	9,420		5.6	%
Tax credits	(2,213)		(0.6)	%	(1,716)		(0.7)	%	(440)		(0.3)	%
Changes in valuation allowance	—		—		1,032		0.4	%	—		—
Nontaxable and nondeductible items:
Corporate-owned life insurance	(2,242)		(0.7)	%	(1,842)		(0.7)	%	(2,196)		(1.3)	%
Other	848		0.3	%	589		0.2	%	197		0.1	%
Changes in unrecognized tax benefits	(182)		(0.1)	%	(1,849)		(0.7)	%	(23)		—	%
Other adjustments:
Amortization of excess deferred taxes	(10,172)		(3.1)	%	(19,656)		(7.7)	%	(23,112)		(13.6)	%
MountainWest sale	—		—		—		—		9,989		5.9	%
Total income tax expense and effective income tax rate	$	96,037	29.0	%	$	33,157	13.0	%	$	29,410	17.4	%

(1) State taxes in Arizona made up the majority (greater than 50%) of the tax effect in this category. In addition, this reflects the impact of the revised state apportionment rates recorded in 2025.

A reconciliation of the U.S. federal statutory rate to the Southwest Gas effective income tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2025				2024				2023
(Thousands of dollars)	Amount		Percent		Amount		Percent		Amount		Percent
U.S. federal statutory income tax	$	74,157	21.0	%	$	64,001	21.0	%	$	56,821	21.0	%
State and local income tax, net of deferred benefit (1)	(7,298)		(2.1)	%	2,946		1.0	%	10,773		4.0	%
Tax credits	(2,213)		(0.6)	%	(1,716)		(0.6)	%	(440)		(0.2)	%

Nontaxable and nondeductible items	(1,470)		(0.3)	%	(1,057)		(0.3)	%	(2,100)		(0.7)	%
Changes in unrecognized tax benefits	(182)		(0.1)	%	(1,849)		(0.6)	%	(23)		—	%
Other adjustments:
Amortization of excess deferred taxes	(10,171)		(2.9)	%	(19,656)		(6.5)	%	(22,869)		(8.5)	%
Total income tax expense and effective income tax rate	$	52,823	15.0	%	$	42,669	14.0	%	$	42,162	15.6	%

(1) State taxes in Arizona made up the majority (greater than 50%) of the tax effect in this category. In addition, this reflects the impact of the revised state apportionment rates recorded in 2025.

Schedule of Income Taxes Paid

Total cash paid for income taxes, net of refunds, are detailed below. Please note that the table below includes totals for both continuing and discontinued operations.


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Federal	$	24,500	$	(350)	$	(2,421)
State:
California	8,502		—		—
Illinois	2,060		—		—
Indiana	—		509		—
Maryland	—		1,104		—
Massachusetts	—		512		—
Pennsylvania	—		—		837
Texas	—		—		723
Other states	4,197		800		1,045
Canada	1,229		7,330		9,181
Total income taxes paid, net	$	40,488	$	9,905	$	9,365

Income taxes paid, net of refunds, are as follows:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Federal	$	585	$	—	$	—
California	421		—		—
Total income taxes paid, net	$	1,006	$	—	$	—

Schedule of Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2025		2024
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	78,826	$	81,802
Net operating losses	146,287		144,172
Other	3,848		2,107
Valuation allowance	—		(1,117)
Total deferred tax assets	228,961		226,964
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822		1,020,885
Regulatory balancing accounts	1,459		3,988
Debt-related costs	1,055		1,384
Employee benefits	29,680		24,118
Other	54,257		34,571
Total deferred tax liabilities	1,206,273		1,084,946
Net noncurrent deferred tax liabilities	$	977,312	$	857,982

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2025		2024
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	78,826	$	81,802
Net operating losses	89,174		188,458
Other	3,258		2,543
Total deferred tax assets	171,258		272,803
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822		1,064,187
Regulatory balancing accounts	1,459		4,157
Debt-related costs	1,055		1,443
Employee benefits	31,865		27,337
Other	44,978		29,928
Total deferred tax liabilities	1,199,179		1,127,052
Net deferred tax liabilities	$	1,027,921	$	854,249

Schedule of Unrecognized Tax Benefits Roll Forward

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2025		2024
Unrecognized tax benefits at beginning of year	$	773	$	2,622
Gross increases – tax positions in prior period	95		83
Gross increases – current period tax positions	—		171
Gross decreases – current period tax positions	(277)		—
Lapse in statute of limitations	—		(2,103)
Unrecognized tax benefits at end of year	$	591	$	773

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2025		2024
Unrecognized tax benefits at beginning of year	$	773	$	2,622
Gross increases – tax positions in prior period	95		83
Gross increases – current period tax positions	—		171
Gross decreases – current period tax positions	(277)		—
Lapse in statute of limitations	—		(2,103)
Unrecognized tax benefits at end of year	$	591	$	773

Share-Based Compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Share-Based Compensation

Note 12 - Share-Based Compensation

At December 31, 2025, the following share-based compensation plans existed at the Company: an omnibus incentive plan and a restricted stock/unit plan. The fair value of share grants is primarily based on the closing price of the Company’s stock on the date of grant. All share grants in 2025, including time-lapse restricted stock units and performance stock units, occurred under the omnibus incentive plan. The table below shows total share-based plan compensation expense which was recognized in the Company’s Consolidated Statements of Income:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Share-based compensation expense - continuing operations	$	14,631	$	11,372	$	6,228
Share-based compensation expense - discontinued operations	8,705		3,527		1,851
Total share-based compensation expense	$	23,336	$	14,899	$	8,079

Tax benefit related to share-based compensation - continuing operations	$	2,244	$	2,051	$	1,495
Tax benefit related to share-based compensation - discontinued operations	1,539		797		444
Total tax benefit	$	3,783	$	2,848	$	1,939

Omnibus Incentive Plan

The omnibus incentive plan is used to promote the long-term growth and profitability of the Company, including its subsidiaries, by providing directors, employees, and certain other individuals, with incentives to increase stockholder value and otherwise contribute to the success of the Company. In addition, the plan enables the Company to attract, retain, and reward the best available persons for positions of responsibility. The omnibus incentive plan provides for the grant of stock options, stock appreciation rights, restricted stock, restricted stock units, performance stock units, and other equity-based, as well as cash, awards. Employees, directors, and consultants who provide services to the Company or any subsidiary may be eligible under this plan. For grants under the omnibus incentive plan, directors continue to immediately vest in the shares upon grant but are provided the option to defer receipt of equity compensation until they leave the Board.

Performance-based incentive opportunities under the ongoing programs of the omnibus plan were granted to all officers of Southwest Gas in the form of performance stock units and are based, depending on the officer, on consolidated or Southwest Gas earnings per share, utility net income, and utility return on equity, with an adjustment, where relevant, based on total shareholder return compared to peer companies and, for all participants, measured over a three-year forward performance period. Performance stock units are restricted based on vesting, and in this case, further subject to future performance determinations against relevant benchmarks. From time to time, special awards may be granted, as permissible under the omnibus plan, that are recognized based on the relevant conditions of the grant and accounting determinations for recognition and, in 2024, three officers received special performance stock unit awards with accelerated vesting provisions for certain termination events. In 2025, one officer received a special performance stock unit award with accelerated vesting provisions for certain termination events. Southwest Gas recorded $6.2 million, $5.2 million, and $1.1 million of estimated compensation expense associated with the collective performance stock unit awards during 2025, 2024, and 2023, respectively. Performance stock unit awards provide for accelerated vesting in certain limited termination events, with vesting in the ultimate award, if any, generally prorated based on the number of months of employment during the three-year forward vesting period.

Conversely, with regard to management, grants under the omnibus plan are of time-lapse restricted stock units with graded vesting (and issuance in the form of common stock) occurring (following grant) at the rate of 40% at the end of year one and 30% at the end of years two and three. Accelerated vesting occurs based on retirement eligibility.

Restricted stock/units under the restricted stock/unit plan were previously granted to attract, motivate, retain, and reward key employees of the Company with an incentive to attain high levels of individual performance and improved financial performance. The legacy plan was also established to attract, motivate, and retain experienced and knowledgeable directors. All remaining shares under the legacy restricted stock/unit plan (in regard to employees) were issued during 2021; remaining unissued legacy program shares relate solely to directors, and such shares were immediately vested at the time of grant, with distribution to occur when service on the Board ends.

No new grants are made under the legacy plan as all future stock-based incentive compensation, including with regard to restricted stock, is granted under programs of the omnibus incentive plan, which for directors, with advance election, issuance may occur upon leaving Board service.

The following table summarizes the activity of the omnibus incentive plan and restricted stock/units programs as of December 31, 2025:


(Thousands of shares)	Performance Stock Units	Weighted-average grant date fair value		Restricted Stock Units/Director Deferred Stock Units	Weighted-average grant date fair value
Nonvested/unissued at December 31, 2024	326	$	64.95	232	$	55.39
Granted	100	76.87		84	75.42
Dividends	1	—		7	—
Forfeited or expired	(32)	68.85		—	—
Vested and issued (1)	(146)	68.34		(115)	56.90
Nonvested/unissued at December 31, 2025	249	$	66.96	208	$	60.68

(1) Includes shares for retiree payouts and those converted for taxes.

The weighted average grant date fair value of performance stock units and time-lapse restricted stock units granted in 2024 was $68.54 and $62.55, respectively, and in 2023 was $62.78 for performance stock units and $62.83 for time-lapse restricted stock units.

As of December 31, 2025, total compensation cost related to all unvested shares not yet recognized is $7.3 million, which is expected to be recognized over a weighted average period of 1.6 years.

Income Taxes - Schedule of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Current:
Federal						$ (24)	$ 1,289	$ (66)
State						1,777	570	402
Total current tax expense						1,753	1,859	336
Deferred:
Federal						55,547	28,627	19,400
State						38,737	2,671	9,674
Total deferred tax expense						94,284	31,298	29,074
Total income tax expense		$ 79,865		$ 107,534		96,037	33,157	29,410
Southwest Gas Corporation
Current:
Federal						(96,017)	(12)	(21)
State						(9,051)	105	98
Total current tax expense						(105,068)	93	77
Deferred:
Federal						156,138	39,730	30,980
State						1,753	2,846	11,105
Total deferred tax expense						157,891	42,576	42,085
Total income tax expense	$ (1,245)	$ (7,235)	$ 39,155	$ 31,920	$ 30,675	$ 52,823	$ 42,669	$ 42,162

Regulated Operations Plant - Narrative (Details)	12 Months Ended			36 Months Ended
Regulated Operations Plant - Narrative (Details)	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2025
Public Utility, Property, Plant and Equipment [Line Items]
Annual utility depreciation and amortization expense percentage	2.70%	2.60%	2.60%
Gas, Transmission and Distribution Plant
Public Utility, Property, Plant and Equipment [Line Items]
Annual utility depreciation and amortization expense percentage				2.30%

Regulatory Assets and Liabilities - Schedule of Components of Other Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ (1,195,684)	$ (1,124,828)
Infrastructure replacement programs and similar
Regulatory Liabilities [Line Items]
Regulatory liabilities	(2,484)	(2,069)
Environmental compliance programs
Regulatory Liabilities [Line Items]
Regulatory liabilities	(6,710)	(733)
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	(1,180)	(663)
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ (10,374)	$ (3,465)

Receivables and Related Allowances

12 Months Ended

Dec. 31, 2025

Receivables [Abstract]

Receivables and Related Allowances

Note 7 - Receivables and Related Allowances

Business activity with respect to natural gas utility operations is conducted with customers located within the three-state region of Arizona, Nevada, and California. Southwest Gas’ accounts receivable are short-term in nature with billing due dates customarily not extending beyond one month. Customers’ credit worthiness is assessed upon account creation by evaluation of other utility service or their credit file and related payment history. Although Southwest Gas seeks to minimize its credit risk related to utility operations by requiring security deposits from new customers, imposing late fees, and actively pursuing collection on overdue accounts where possible, some accounts are ultimately not collected. Customer accounts are subject to collection procedures that vary by jurisdiction, such as late fee assessment, notice requirements for disconnection of service, and procedures for actual disconnection and/or reestablishment of service. After disconnection of service, accounts are customarily written off approximately two months after disconnection if the account remains inactive. Depending upon the jurisdiction, reestablishment of service requires both the payment of previously unpaid balances and additional deposit requirements. Generally, costs related to uncollectible accounts are included in the ratemaking process as a cost of service. However, the Nevada and California jurisdictions have certain regulatory mechanisms in place to separately track and collect portions of uncollectible accounts through the mechanisms. Eligible amounts are deferred and collected through a surcharge in the ratemaking process. Southwest Gas continues to actively work with customers experiencing financial hardship by means of flexible payment options and partnering with assistance agencies. Provisions for uncollectible accounts are recorded monthly based on each customer’s current ability to pay amounts that are due, payment history, consideration of current conditions, customer and rate composition, regulatory requirements, and write-off processes.

The table below contains information about Southwest Gas’ gas utility customer accounts receivable balance (net of allowance) at December 31, 2025 and 2024:


	December 31,
(Thousands of dollars)	2025		2024
Gas utility customer accounts receivable balance	$	163,752	$	194,177

The following table represents the percentage of customers in each of Southwest Gas’ three states at December 31, 2025, which was consistent with the prior year:


Percent of customers by state:
Arizona	54	%
Nevada	37	%
California	9	%

Southwest Gas activity in the allowance account for uncollectibles is summarized as follows:


(Thousands of dollars)	Allowance for Uncollectibles
Balance, December 31, 2022	$	4,830
Additions charged to expense	11,877
Accounts written off, less recoveries	(10,612)
Balance, December 31, 2023	6,095
Additions charged to expense	12,400
Accounts written off, less recoveries	(11,428)
Balance, December 31, 2024	7,067
Additions charged to expense	11,955
Accounts written off, less recoveries	(11,372)
Balance, December 31, 2025	$	7,650

The table above does not provide the effect for amounts included in the regulatory tracking mechanisms noted earlier.

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 773	$ 2,622
Gross increases – tax positions in prior period	95	83
Gross increases – current period tax positions	0	171
Gross decreases – current period tax positions	(277)	0
Lapse in statute of limitations	0	(2,103)
Unrecognized tax benefits at end of year	591	773
Southwest Gas Corporation
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	773	2,622
Gross increases – tax positions in prior period	95	83
Gross increases – current period tax positions	0	171
Gross decreases – current period tax positions	(277)	0
Lapse in statute of limitations	0	(2,103)
Unrecognized tax benefits at end of year	$ 591	$ 773

Revision of Previously Issued Financial Statements (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Changes and Error Corrections [Abstract]

Schedule of Error Corrections and Prior Period Adjustments

The effects of the correction of the errors on the Consolidated Financial Statements are as follows:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEET
(In thousands)

	December 31, 2024
	As Reported(1)		Adjustments		As Revised
ASSETS


Accounts receivable, net of allowance	$	202,947	$	(2,100)	$	200,847



Total current assets	859,055		(2,100)		856,955
Total assets	$	9,533,825	$	(2,100)	$	9,531,725
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,096,149	$	(36,376)	$	1,059,773
Total equity	3,271,862		(36,376)		3,235,486
Total capitalization	6,776,339		(36,376)		6,739,963
Accounts payable	190,612		1,997		192,609
Deferred purchased gas costs	255,398		(1,997)		253,401


Total current liabilities	769,026		—		769,026
Deferred income taxes and investment tax credits, net	819,973		34,276		854,249

Total deferred income taxes and other credits	1,988,460		34,276		2,022,736
Total capitalization and liabilities	$	9,533,825	$	(2,100)	$	9,531,725
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,475,216	$	7,774	$	2,482,990
Net cost of gas sold	1,150,005		7,359		1,157,364
Total operating expenses	2,062,885		7,359		2,070,244
Operating income	412,331		415		412,746
Income before income taxes	304,350		415		304,765
Income tax expense (benefit)	43,174		(505)		42,669
Net income	$	261,176	$	920	$	262,096






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,499,564	$	(5,344)	$	2,494,220
Net cost of gas sold	1,246,901		4,466		1,251,367
Operations and maintenance	511,646		(1,259)		510,387
Total operating expenses	2,141,270		3,207		2,144,477
Operating income (loss)	358,294		(8,551)		349,743
Income (loss) before income taxes	279,125		(8,551)		270,574
Income tax expense	36,899		5,263		42,162
Net income (loss)	$	242,226	$	(13,814)	$	228,412


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Net income	$	261,176	$	920	$	262,096
Comprehensive income	$	263,323	$	920	$	264,243






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Comprehensive income (loss)	$	239,939	$	(13,814)	$	226,125


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)

	Year Ended December 31, 2024
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	261,176	$	920	$	262,096
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	69,459		(505)		68,954
Changes in current assets and liabilities:
Accounts receivable, net of allowances	66,248		2,100		68,348
Deferred purchased gas costs	706,896		8,062		714,958
Accounts payable	(19,032)		(703)		(19,735)
Other current assets and liabilities	(57,917)		(9,874)		(67,791)
Net cash provided by operating activities	$	1,252,982	$	—	$	1,252,982
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.






	Year Ended December 31, 2023
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	66,611		5,263		71,874
Changes in current assets and liabilities:
Deferred purchased gas costs	192,182		(3,956)		188,226
Accounts payable	(260,403)		7,164		(253,239)
Other current assets and liabilities	14,516		5,343		19,859


Net cash provided by operating activities	$	391,545	$	—	$	391,545
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)

	As Reported		Adjustments		As Revised
Retained earnings, December 31, 2022	$	935,355	$	(23,482)	$	911,873
Total equity, December 31, 2022	2,569,175		(23,482)		2,545,693
Net income (loss) for the year ended December 31, 2023	242,226		(13,814)		228,412
Retained earnings, December 31, 2023	1,018,474		(37,296)		981,178
Total equity, December 31, 2023	3,183,615		(37,296)		3,146,319
Net income for the year ended December 31, 2024	261,176		920		262,096
Retained earnings, December 31, 2024	1,096,149		(36,376)		1,059,773
Total equity, December 31, 2024	$	3,271,862	$	(36,376)	$	3,235,486

The effects of the Company’s prior-period errors on our Condensed Consolidated Financial Statements are as follows:


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	June 30, 2025
	As Reported		Adjustments		As Restated(1)






















CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	769,723	$	(27,271)	$	742,452
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,674,657		(27,271)		3,647,386

Total equity	4,115,805		(27,271)		4,088,534


Total capitalization	8,520,371		(27,271)		8,493,100













Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	927,486		27,271		954,757



Total deferred income taxes and other credits	2,279,069		27,271		2,306,340
Total capitalization and liabilities	$	12,213,945	$	—	$	12,213,945

(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	September 30, 2025
	As Reported		Adjustments		As Restated
























CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	999,399	$	(35,113)	$	964,286
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,928,679		(35,113)		3,893,566

Total equity	3,928,679		(35,113)		3,893,566

Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	7,435,799		(110,113)		7,325,686
Current liabilities:
Current maturities of long-term debt	—		75,000		75,000










Total current liabilities	804,703		75,000		879,703
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	905,604		35,113		940,717



Total deferred income taxes and other credits	2,088,077		35,113		2,123,190
Total capitalization and liabilities	$	10,328,579	$	—	$	10,328,579


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
(In thousands, except per share amounts)
(Unaudited)


	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated(1)		As Reported		Adjustments		As Restated(1)

















Income tax expense (benefit)	$	52,594	$	27,271	$	79,865	$	80,263	$	27,271	$	107,534


Net income (loss)	(10,329)		(27,271)		(37,600)		98,858		(27,271)		71,587

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	(12,883)	$	(27,271)	$	(40,154)	$	100,987	$	(27,271)	$	73,716

Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.:


Basic	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02




Diluted	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02

Weighted average shares:
Basic	72,088				72,088		72,050				72,050
Diluted	72,088				72,088		72,195				72,195
(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated















Income tax expense (benefit)	$	(803)	$	7,842	$	7,039	$	36,059	$	35,113	$	71,172
Income (loss) from continuing operations	4,175		(7,842)		(3,667)		165,003		(35,113)		129,890

Net income (loss)	267,959		(7,842)		260,117		366,817		(35,113)		331,704

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	270,476	$	(7,842)	$	262,634	$	371,463	$	(35,113)	$	336,350

Basic earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.29	$	(0.49)	$	1.80

Net earnings (loss) per share - basic	$	3.75	$	(0.11)	$	3.64	$	5.15	$	(0.49)	$	4.66

Diluted earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.28	$	(0.49)	$	1.79

Net earnings (loss) per share - diluted	$	3.74	$	(0.11)	$	3.63	$	5.14	$	(0.49)	$	4.65

Weighted average shares:
Basic	72,209				72,209		72,104				72,104
Diluted	72,405				72,405		72,265				72,265


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	(10,329)	$	(27,271)	$	(37,600)	$	98,858	$	(27,271)	$	71,587









Comprehensive income (loss)	(3,351)		(27,271)		(30,622)		106,208		(27,271)		78,937

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	(6,970)	$	(27,271)	$	(34,241)	$	107,252	$	(27,271)	$	79,981






	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	267,959	$	(7,842)	$	260,117	$	366,817	$	(35,113)	$	331,704









Comprehensive income (loss)	266,566		(7,842)		258,724		372,774		(35,113)		337,661

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	269,879	$	(7,842)	$	262,037	$	377,131	$	(35,113)	$	342,018


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	98,858	$	(27,271)	$	71,587


Adjustments to reconcile net income (loss) to net cash provided by operating activities:

Deferred income taxes	94,033		27,271		121,304
Net cash provided by operating activities	$	417,611	$	—	$	417,611


	Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	366,817	$	(35,113)	$	331,704

Income (loss) from continuing operations, net of income tax	165,003		(35,113)		129,890
Adjustments to reconcile net income to net cash provided by operating activities:

Deferred income taxes	48,141		35,113		83,254
Net cash provided by operating activities of continuing operations	509,136		—		509,136

Net cash provided by operating activities	$	474,508	$	—	$	474,508


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Restated


Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended June 30, 2025	$	(12,883)	$	(27,271)	$	(40,154)
Retained earnings, June 30, 2025	769,723		(27,271)		742,452
Total equity attributable to Southwest Gas Holdings, Inc., June 30, 2025	3,674,657		(27,271)		3,647,386
Total equity, June 30, 2025	4,115,805		(27,271)		4,088,534
Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended September 30, 2025	270,476		(7,842)		262,634
Retained earnings, September 30, 2025	999,399		(35,113)		964,286
Total equity attributable to Southwest Gas Holdings, Inc., September 30, 2025	3,928,679		(35,113)		3,893,566
Total equity, September 30, 2025	$	3,928,679	$	(35,113)	$	3,893,566

The impacts of the revisions are presented in the tables below:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	March 31, 2025
	As Reported		Adjustments		As Revised



CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,238,775	$	(36,723)	$	1,202,052
Total equity	3,416,872		(36,723)		3,380,149
Total capitalization	6,922,224		(36,723)		6,885,501


Deferred income taxes and investment tax credits, net	857,986		36,723		894,709
Total deferred income taxes and other credits	2,025,235		36,723		2,061,958
Total capitalization and liabilities	$	9,679,467	$	—	$	9,679,467






	June 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,227,760	$	(24,754)	$	1,203,006
Total equity	3,408,373		(24,754)		3,383,619
Total capitalization	6,914,610		(24,754)		6,889,856


Deferred income taxes and investment tax credits, net	871,647		24,754		896,401
Total deferred income taxes and other credits	2,047,726		24,754		2,072,480
Total capitalization and liabilities	$	9,688,433	$	—	$	9,688,433






	September 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,233,196	$	(23,931)	$	1,209,265
Total equity	3,416,463		(23,931)		3,392,532
Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	6,923,583		(98,931)		6,824,652
Current maturities of long-term debt	—		75,000		75,000
Total current liabilities	751,278		75,000		826,278
Deferred income taxes and investment tax credits, net	872,344		23,931		896,275
Total deferred income taxes and other credits	2,050,616		23,931		2,074,547
Total capitalization and liabilities	$	9,725,477	$	—	$	9,725,477


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	746,416	$	2,100	$	748,516
Operating income	214,979		2,100		217,079
Income before income taxes	179,650		2,100		181,750
Income tax expense	36,708		2,447		39,155
Net income (loss)	$	142,942	$	(347)	$	142,595







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	396,318	$	—	$	396,318	$	1,142,734	$	2,100	$	1,144,834
Operating income	65,342		—		65,342		280,321		2,100		282,421
Income before income taxes	38,411		—		38,411		218,061		2,100		220,161
Income tax expense (benefit)	4,734		(11,969)		(7,235)		41,442		(9,522)		31,920
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	316,911	$	—	$	316,911	$	1,459,645	$	2,100	$	1,461,745
Operating income	37,977		—		37,977		318,298		2,100		320,398
Income before income taxes	5,098		—		5,098		223,159		2,100		225,259
Income tax expense (benefit)	(422)		(823)		(1,245)		41,020		(10,345)		30,675
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Net income (loss)	$	142,942	$	(347)	$	142,595
Comprehensive income (loss)	$	143,210	$	(347)	$	142,863







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241
Comprehensive income	$	33,944	$	11,969	$	45,913	$	177,154	$	11,622	$	188,776







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584
Comprehensive income	$	5,789	$	823	$	6,612	$	182,943	$	12,445	$	195,388


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Three Month Ended March 31, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	142,942	$	(347)	$	142,595
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	37,928		2,447		40,375
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(11,117)		(2,100)		(13,217)
Deferred purchased gas costs	53,865		1,997		55,862
Accounts payable	(44,691)		(1,997)		(46,688)
Net cash provided by operating activities	$	285,832	$	—	$	285,832







	Six Month Ended June 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	176,619	$	11,622	$	188,241
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	51,504		(9,522)		41,982
Changes in current assets and liabilities:
Accounts receivable, net of allowance	68,311		(2,100)		66,211
Deferred purchased gas costs	120,709		1,997		122,706
Accounts payable	(69,232)		(1,997)		(71,229)
Net cash provided by operating activities	$	459,287	$	—	$	459,287







	Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	182,139	$	12,445	$	194,584
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	52,890		(10,345)		42,545
Changes in current assets and liabilities:
Accounts receivable, net of allowance	92,372		(2,100)		90,272
Deferred purchased gas costs	114,768		1,997		116,765
Accounts payable	(66,237)		(1,997)		(68,234)
Net cash provided by operating activities	$	526,359	$	—	$	526,359


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Revised


Net income (loss), for the three months ended March 31, 2025	$	142,942	$	(347)	$	142,595
Retained earnings, March 31, 2025	1,238,775		(36,723)		1,202,052
Total Equity, March 31, 2025	3,416,872		(36,723)		3,380,149
Net income for the three months ended June 30, 2025	33,677		11,969		45,646
Retained earnings, June 30, 2025	1,227,760		(24,754)		1,203,006
Total Equity, June 30, 2025	3,408,373		(24,754)		3,383,619
Net income (loss) for the three months ended September 30, 2025	5,520		823		6,343
Retained earnings, September 30, 2025	1,233,196		(23,931)		1,209,265
Total Equity, September 30, 2025	$	3,416,463	$	(23,931)	$	3,392,532

Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	$ 519,737	$ 494,088
Total regulatory liabilities	(1,195,684)	(1,124,828)
Net regulatory assets (liabilities)	$ (675,947)	(630,740)
Accrued pension and other postretirement benefit costs, recovery period	5 years
Deferred purchased gas costs
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	$ (310,085)	(255,398)
Accumulated removal costs
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(496,000)	(472,000)
Unamortized gain on reacquired debt
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(4,963)	(5,500)
Regulatory excess deferred/other taxes and gross-up
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(348,243)	(363,353)
Regulatory excess deferred/other taxes and gross-up \| Other current liabilities
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(10,000)	(21,000)
Margin, interest - and property tax-tracking
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(26,019)	(25,112)
Other
Regulatory Assets And Liabilities [Line Items]
Total regulatory liabilities	(10,374)	(3,465)
Accrued pension and other postretirement benefit costs
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	246,444	299,961
Deferred purchased gas costs
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	5,214	13,807
Unamortized premium on reacquired debt
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	10,016	11,529
Accrued absence time
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	$ 22,430	21,231
Regulatory assets, accrued absence time, lag period	1 year
Margin, interest - and property tax-tracking
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	$ 142,813	57,477
Regulatory assets, margin, interest and property tax-tracking, recovery period	24 months
Other
Regulatory Assets And Liabilities [Line Items]
Total regulatory assets	$ 92,820	$ 90,083

Segment Information (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Schedule of Segment Reporting Information

The financial information pertaining to the Natural Gas Distribution and Pipeline and Storage segments as of and for the year ended December 31, 2023 is presented in the tables below. The accounting policies of the segments are the same as those described in Note 2 - Summary of Significant Accounting Policies. In order to reconcile to net income as disclosed in the Consolidated Statements of Income, an Other column is included below associated with certain expenses that represent the corporate and administrative activities associated with Southwest Gas Holdings, such as Operations and maintenance expenses and net interest deduction.


	Year Ended December 31, 2023
(Thousands of dollars)	Natural Gas Distribution		Pipeline and Storage (1)		Other		Total
Revenues from external customers	$	2,536,079	$	35,132	$	—	$	2,571,211
Alternative revenue program and other revenues	(36,515)		—		—		(36,515)
Total segment revenues	2,499,564		35,132		—		2,534,696
Less:
Net cost of gas sold	1,246,901		6,368		—		1,253,269
Operations and maintenance expense	511,646		11,378		9,985		533,009
Other segment items (2)	461,892		24,419		92,703		579,014
Income (loss) before income taxes	279,125		(7,033)		(102,688)		169,404
Income tax expense (benefit)	36,899		9,255		(16,744)		29,410
Income (loss) from continuing operations	242,226		(16,288)		(85,944)		139,994
Income from discontinued operations, net of taxes							15,523
Net income							155,517
Net income attributable to noncontrolling interests							4,628
Net income attributable to Southwest Gas Holdings, Inc.							$	150,889

(1) The information for the year ended December 31, 2023 presented for MountainWest reflects activity from January 1, 2023 through February 13, 2023 (the last full day of its ownership by the Company).

(2) Other segment items for each reportable segment includes:

•Natural Gas Distribution: Depreciation and amortization, Taxes other than income taxes, Net interest deductions, and Other income (deductions).

•Pipeline and Storage: Depreciation and amortization, Taxes other than income taxes, Goodwill impairment and loss on sale, Net interest deductions, and Other income (deductions).


Other segment disclosures	Year Ended December 31, 2023
(Thousands of dollars)	Natural Gas Distribution		Pipeline and Storage (1)		Other		Total
Interest income	$	50,757	$	—	$	—	$	50,757
Interest expense	$	149,830	$	2,200	$	42,780	$	194,810
Depreciation and amortization	$	295,462	$	—	$	—	$	295,462
Goodwill impairment and loss on sale	$	—	$	21,215	$	50,015	$	71,230
Segment assets	$	9,268,571	$	—	$	8,735	$	9,277,306
Capital expenditures	$	762,081	$	3,790	$	—	$	765,871

CONSOLIDATED STATEMENTS OF EQUITY - Southwest - USD ($) $ in Thousands	Total	Southwest Gas Corporation	Common stock shares	Common stock shares Southwest Gas Corporation	Additional Paid-in Capital	Additional Paid-in Capital Southwest Gas Corporation	AOCI	AOCI Southwest Gas Corporation	Retained Earnings	Retained Earnings Southwest Gas Corporation
Beginning balance (in shares) at Dec. 31, 2022			67,119,000	47,482,000
Beginning balance at Dec. 31, 2022	$ 3,058,759	$ 2,545,693	$ 68,749	$ 49,112	$ 2,287,183	$ 1,622,969	$ (44,242)	$ (38,261)	$ 747,069	$ 911,873
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	150,889	228,412							150,889	228,412
Dividends declared to Southwest Gas Holdings, Inc.	(178,485)	(158,600)							(178,485)	(158,600)
Share-based compensation		3,101				3,608				(507)
Contributions from Southwest Gas Holdings, Inc.		530,000				530,000
Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax	(2,287)	(2,287)					(2,287)	(2,287)
Ending balance (in shares) at Dec. 31, 2023			71,564,000	47,482,000
Ending balance at Dec. 31, 2023	3,310,036	3,146,319	$ 73,194	$ 49,112	2,541,790	2,156,577	(43,787)	(40,548)	738,839	981,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	198,815	262,096							198,815	262,096
Dividends declared to Southwest Gas Holdings, Inc.	(178,811)	(182,900)							(178,811)	(182,900)
Share-based compensation		7,824				8,425				(601)
Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax	$ 2,147	2,147					2,147	2,147
Ending balance (in shares) at Dec. 31, 2024	71,782,756		71,783,000	47,482,000
Ending balance at Dec. 31, 2024	$ 3,681,422	3,235,486	$ 73,413	$ 49,112	2,721,343	2,165,002	(49,218)	(38,401)	758,649	1,059,773
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		142,595
Ending balance at Mar. 31, 2025		3,380,149								1,202,052
Beginning balance (in shares) at Dec. 31, 2024	71,782,756		71,783,000	47,482,000
Beginning balance at Dec. 31, 2024	$ 3,681,422	3,235,486	$ 73,413	$ 49,112	2,721,343	2,165,002	(49,218)	(38,401)	758,649	1,059,773
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	439,826	300,308							439,826	300,308
Dividends declared to Southwest Gas Holdings, Inc.	(179,845)	(44,609)							(179,845)	(44,609)
Share-based compensation		9,926				10,487				(561)
Contributions from Southwest Gas Holdings, Inc.		20,000				20,000
Net actuarial (loss) gain arising during period, less amortization of unamortized benefit plan cost, net of tax	$ 3,855	3,855					3,855	3,855
Ending balance (in shares) at Dec. 31, 2025	72,224,593		72,224,000	47,482,000
Ending balance at Dec. 31, 2025	$ 3,961,119	3,524,966	$ 73,854	$ 49,112	$ 2,898,965	$ 2,195,489	$ (34,546)	$ (34,546)	1,022,846	1,314,911
Beginning balance at Mar. 31, 2025		3,380,149								1,202,052
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(40,154)	45,646
Ending balance at Jun. 30, 2025	4,088,534	3,383,619							742,452	1,203,006
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	262,634	6,343
Ending balance at Sep. 30, 2025	$ 3,893,566	$ 3,392,532							$ 964,286	$ 1,209,265

Amount of equity (deficit) attributable to parent and noncontrolling interest. Excludes temporary equity.

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Reference 56: http://www.xbrl.org/2003/role/disclosureRef
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Reference 57: http://www.xbrl.org/2003/role/disclosureRef
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Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt

Debt (Tables)

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows.


	December 31,
	2025				2024
(Thousands of dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Southwest Gas Holdings, Inc. and Southwest Gas Corporation:
Debentures:
8% Series, due 2026	$	75,000	$	76,388	$	75,000	$	77,898
Medium-term notes, 7.92% series, due 2027	25,000		26,058		25,000		26,285
Medium-term notes, 6.76% series, due 2027	7,500		7,726		7,500		7,701
Notes, 5.8%, due 2027	300,000		309,090		300,000		306,450
Notes, 3.7%, due 2028	300,000		297,450		300,000		287,460
Notes, 5.45%, due 2028	300,000		307,620		300,000		302,970
Notes, 2.2%, due 2030	450,000		409,365		450,000		385,425
Notes, 4.05%, due 2032	600,000		579,540		600,000		558,120
Notes, 6.1%, due 2041	125,000		130,762		125,000		127,900
Notes, 4.875%, due 2043	250,000		219,350		250,000		210,700
Notes, 3.8%, due 2046	300,000		228,180		300,000		219,390
Notes, 4.15%, due 2049	300,000		237,120		300,000		223,470
Notes, 3.18%, due 2051	300,000		205,710		300,000		187,680
Unamortized discount and debt issuance costs	(23,207)				(26,477)
	3,309,293				3,306,023

Industrial development revenue bonds:
Tax-exempt Series A, due 2028	50,000		50,000		50,000		50,000
2003 Series A, due 2038	50,000		50,000		50,000		50,000
2008 Series A, due 2038	50,000		50,000		50,000		50,000
2009 Series A, due 2039	50,000		50,000		50,000		50,000
Unamortized discount and debt issuance costs	(1,281)				(1,546)
	198,719				198,454
Less: current maturities	75,000				—
Southwest Gas Holdings, Inc. and Southwest Gas Corporation total long-term debt, less current maturities	$	3,433,012			$	3,504,477

Schedule of Effective Interest Rates on Variable-Rate IDRBs

The effective interest rates on Southwest Gas’ variable-rate IDRBs are included in the table below:


	December 31,
	2025		2024
2003 Series A	3.50	%	4.86	%
2008 Series A	3.84	%	4.89	%
2009 Series A	3.75	%	4.73	%
Tax-exempt Series A	3.10	%	4.29	%

Schedule of Estimated Maturities of Long-Term Debt

Estimated maturities of long-term debt and the current portion of long-term debt for the next five years are:


(Thousands of dollars)	2026		2027		2028		2029		2030
Southwest Gas Holdings, Inc. and Southwest Gas Corporation:
Debentures	$	75,000	$	332,500	$	650,000	$	—	$	450,000




Total	$	75,000	$	332,500	$	650,000	$	—	$	450,000

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Current Fiscal Year End Date

Revision of Previously Issued Financial Statements - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ 260,117	$ (37,600)		$ 71,587	$ 331,704	$ 435,180	$ 204,836	$ 155,517
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				121,304	83,254	118,112	57,730	59,392
Changes in current assets and liabilities:
Accounts receivable, net of allowances						32,411	66,275	(38,387)
Deferred purchased gas costs						63,280	706,896	177,177
Accounts payable						13,172	(20,006)	(256,399)
Other current assets and liabilities						(97,689)	(57,160)	16,837
Net cash provided by operating activities				417,611	474,508	556,076	1,355,780	509,211
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	6,343	45,646	$ 142,595	188,241	194,584	300,308	262,096	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			40,375	41,982	42,545	172,454	68,954	71,874
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(13,217)	66,211	90,272		68,348
Deferred purchased gas costs			55,862	122,706	116,765	65,277	714,958	188,226
Accounts payable			(46,688)	(71,229)	(68,234)	11,086	(19,735)	(253,239)
Other current assets and liabilities						(97,340)	(67,791)	19,859
Net cash provided by operating activities			285,832	459,287	526,359	$ 618,815	1,252,982	391,545
As Reported
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	267,959	(10,329)		98,858	366,817
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				94,033	48,141
Changes in current assets and liabilities:
Net cash provided by operating activities				417,611	474,508
As Reported \| Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	5,520	33,677	142,942	176,619	182,139		261,176	242,226
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			37,928	51,504	52,890		69,459	66,611
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(11,117)	68,311	92,372		66,248
Deferred purchased gas costs			53,865	120,709	114,768		706,896	192,182
Accounts payable			(44,691)	(69,232)	(66,237)		(19,032)	(260,403)
Other current assets and liabilities							(57,917)	14,516
Net cash provided by operating activities			285,832	459,287	526,359		1,252,982	391,545
Adjustments
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				27,271	35,113
Changes in current assets and liabilities:
Deferred purchased gas costs							(74,300)	(294,900)
Other current assets and liabilities							74,300	294,900
Net cash provided by operating activities				0	0
Adjustments \| Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ 823	$ 11,969	(347)	11,622	12,445		920	(13,814)
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			2,447	(9,522)	(10,345)		(505)	5,263
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(2,100)	(2,100)	(2,100)		2,100
Deferred purchased gas costs			1,997	1,997	1,997		8,062	(3,956)
Accounts payable			(1,997)	(1,997)	(1,997)		(703)	7,164
Other current assets and liabilities							(9,874)	5,343
Net cash provided by operating activities			$ 0	$ 0	$ 0		$ 0	$ 0

Summary of Significant Accounting Policies - Schedule of Capitalized and Debt Portion of AFUDC (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Debt portion	$ 2,707	$ 3,126	$ 6,851
Equity portion	5,809	6,597	1,951
AFUDC capitalized as part of regulated operations plant	$ 8,516	$ 9,723	$ 8,802
AFUDC rate	6.77%	6.76%	6.30%

Dispositions - Schedule of Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total current assets classified as discontinued operations	$ 0	$ 601,384
Total noncurrent assets classified as discontinued operations	0	1,927,126
Total current liabilities classified as discontinued operations	0	382,892
Total noncurrent liabilities classified as discontinued operations	$ 0	1,016,726
Discontinued Operations, Disposed of by Sale \| Centuri Holdings, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash		49,019
Accounts receivable, net of allowances		519,610
Other current assets		32,755
Total current assets classified as discontinued operations		601,384
Other property and investments, net		1,025,700
Goodwill		770,046
Deferred income taxes		52,376
Deferred charges and other assets		79,004
Total noncurrent assets classified as discontinued operations		1,927,126
Current maturities of long-term debt		30,018
Accounts payable		140,889
Other current liabilities		211,985
Total current liabilities classified as discontinued operations		382,892
Long-term debt, less current maturities		843,863
Other deferred credits		172,863
Total noncurrent liabilities classified as discontinued operations		$ 1,016,726

Revision of Previously Issued Financial Statements - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Regulated operations revenues						$ 1,940,380	$ 2,475,216	$ 2,534,696
Net cost of gas sold						497,636	1,150,005	1,253,269
Operations and maintenance						544,064	526,679	533,009
Total operating expenses						1,466,494	2,068,744	2,241,721
Operating income (loss)						473,886	406,472	292,975
Income (loss) before income taxes						330,873	254,136	169,404
Income tax expense (benefit)		$ 79,865		$ 107,534		96,037	33,157	29,410
Net income (loss)	$ 262,634	(40,154)		73,716	$ 336,350	439,826	198,815	150,889
Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Regulated operations revenues	316,911	396,318	$ 748,516	1,144,834	1,461,745	1,942,480	2,482,990	2,494,220
Net cost of gas sold						497,636	1,157,364	1,251,367
Operations and maintenance						537,644	520,820	510,387
Total operating expenses						1,460,074	2,070,244	2,144,477
Operating income (loss)	37,977	65,342	217,079	282,421	320,398	482,406	412,746	349,743
Income (loss) before income taxes	5,098	38,411	181,750	220,161	225,259	353,131	304,765	270,574
Income tax expense (benefit)	(1,245)	(7,235)	39,155	31,920	30,675	52,823	42,669	42,162
Net income (loss)	6,343	45,646	142,595	188,241	194,584	$ 300,308	262,096	228,412
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense (benefit)		52,594		80,263
Net income (loss)	270,476	(12,883)		100,987	371,463
As Reported \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Regulated operations revenues	316,911	396,318	746,416	1,142,734	1,459,645		2,475,216	2,499,564
Net cost of gas sold							1,150,005	1,246,901
Operations and maintenance								511,646
Total operating expenses							2,062,885	2,141,270
Operating income (loss)	37,977	65,342	214,979	280,321	318,298		412,331	358,294
Income (loss) before income taxes	5,098	38,411	179,650	218,061	223,159		304,350	279,125
Income tax expense (benefit)	(422)	4,734	36,708	41,442	41,020		43,174	36,899
Net income (loss)	5,520	33,677	142,942	176,619	182,139		261,176	242,226
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income tax expense (benefit)		27,271		27,271
Net income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Adjustments \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Regulated operations revenues	0	0	2,100	2,100	2,100		7,774	(5,344)
Net cost of gas sold							7,359	4,466
Operations and maintenance								(1,259)
Total operating expenses							7,359	3,207
Operating income (loss)	0	0	2,100	2,100	2,100		415	(8,551)
Income (loss) before income taxes	0	0	2,100	2,100	2,100		415	(8,551)
Income tax expense (benefit)	(823)	(11,969)	2,447	(9,522)	(10,345)		(505)	5,263
Net income (loss)	$ 823	$ 11,969	$ (347)	$ 11,622	$ 12,445		$ 920	$ (13,814)

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands			3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Aug. 11, 2025	May 22, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Significant Accounting Policies [Line Items]
Other current assets and liabilities						$ 97,689	$ 57,160	$ (16,837)
Deferred purchased gas costs						$ 63,280	706,896	177,177
Deferred purchased gas costs, recovered or refunded period						1 year
Gas pipe materials and operating supplies						$ 78,100	77,800
Regulatory assets						519,737	494,088
Prepaid insurance premiums						35,400	25,300
Cloud-based software						33,900	24,800
Regulatory asset (liability), including deferred gas costs							(241,600)	465,300
Decoupling Mechanism
Significant Accounting Policies [Line Items]
Regulatory assets						91,100	32,400
Accrued pension and other postretirement benefit costs
Significant Accounting Policies [Line Items]
Regulatory assets						246,444	299,961
Adjustments
Significant Accounting Policies [Line Items]
Other current assets and liabilities							(74,300)	(294,900)
Deferred purchased gas costs							(74,300)	(294,900)
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Other current assets and liabilities						97,340	67,791	(19,859)
Deferred purchased gas costs			$ 55,862	$ 122,706	$ 116,765	65,277	714,958	188,226
Gas pipe materials and operating supplies						78,100	77,800
Prepaid insurance premiums						33,900	25,200
Southwest Gas Corporation \| Adjustments
Significant Accounting Policies [Line Items]
Other current assets and liabilities							9,874	(5,343)
Deferred purchased gas costs			$ 1,997	$ 1,997	$ 1,997		8,062	$ (3,956)
Money Market Funds
Significant Accounting Policies [Line Items]
Money market fund investments						250,500	64,300
Money Market Funds \| Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Money market fund investments						$ 34,400	$ 48,800
Public Offering And Private Placement
Significant Accounting Policies [Line Items]
Sale of stock, number of shares (in shares)	18,823,500	13,207,142

CONSOLIDATED STATEMENTS OF CASH FLOWS - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 435,180	$ 204,836	$ 155,517
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	330,724	303,095	295,462
Deferred income taxes	118,112	57,730	59,392
Gain on sale of property	(1,604)	0	(136)
Share-based compensation expense	14,631	11,372	6,228
Equity AFUDC	(5,809)	(6,597)	(1,951)
Changes in current assets and liabilities:
Accounts receivable, net of allowances	32,411	66,275	(38,387)
Accrued utility revenue	(5,000)	(3,600)	(4,900)
Deferred purchased gas costs	63,280	706,896	177,177
Accounts payable	13,172	(20,006)	(256,399)
Accrued taxes	(20,460)	2,152	(5,386)
Other current assets and liabilities	(97,689)	(57,160)	16,837
Changes in deferred charges and other assets	(62,028)	(47,914)	(32,046)
Changes in other liabilities and deferred credits	(20,415)	(27,890)	(76,610)
Net cash provided by operating activities	556,076	1,355,780	509,211
CASH FLOW FROM INVESTING ACTIVITIES:
Capital expenditures and property additions	(807,866)	(846,590)	(765,871)
Proceeds from the sale of property	5,306	21,377	0
Changes in customer advances	2,023	(5,995)	(8,905)
Other	(955)	(985)	(1,891)
Net cash provided by (used in) investing activities	(24,814)	(921,568)	150,966
CASH FLOW FROM FINANCING ACTIVITIES:
Dividends paid	(178,509)	(177,628)	(174,574)
Issuance of long-term debt, net	0	0	847,759
Change in long-term credit facility and commercial paper	0	0	(50,000)
Issuance of short-term debt	0	0	450,000
Repayment of short-term debt	(550,000)	0	(1,822,748)
Withholding remittance – share-based compensation	(3,063)	(2,677)	(1,777)
Other, including principal payments on finance leases	(4,678)	(3,656)	(3,768)
Net cash used in financing activities	(318,279)	(176,335)	(700,795)
Change in cash and cash equivalents, including discontinued operations	212,856	257,253	(40,345)
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	240,175	278,888	282,626
Increase (decrease) of capital expenditures in Accounts payable or Other current liabilities	16,614	(8,705)	(17,055)
Equity AFUDC capitalized in regulated operations plant	5,809	6,597	1,951
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	300,308	262,096	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	330,724	303,095	295,462
Deferred income taxes	172,454	68,954	71,874
Gain on sale of property	(1,604)	0	(136)
Share-based compensation expense	12,989	10,022	4,877
Equity AFUDC	(5,809)	(6,597)	(1,869)
Changes in current assets and liabilities:
Accounts receivable, net of allowances		68,348
Accrued utility revenue	(5,000)	(3,600)	(4,900)
Deferred purchased gas costs	65,277	714,958	188,226
Accounts payable	11,086	(19,735)	(253,239)
Accrued taxes	(6,043)	1,393	(8,964)
Other current assets and liabilities	(97,340)	(67,791)	19,859
Changes in deferred charges and other assets	(62,003)	(50,216)	(38,975)
Changes in other liabilities and deferred credits	(20,996)	(27,945)	(76,098)
Net cash provided by operating activities	618,815	1,252,982	391,545
CASH FLOW FROM INVESTING ACTIVITIES:
Capital expenditures and property additions	(807,866)	(846,590)	(762,081)
Proceeds from the sale of property	5,306	21,377	0
Changes in customer advances	2,023	(5,995)	(8,905)
Other	2,199	115	414
Net cash provided by (used in) investing activities	(798,338)	(831,093)	(770,572)
CASH FLOW FROM FINANCING ACTIVITIES:
Contributions from parent	20,000	0	530,000
Dividends paid	(89,209)	(178,000)	(150,900)
Issuance of long-term debt, net	0	0	297,759
Change in long-term credit facility and commercial paper	0	0	(50,000)
Issuance of short-term debt	0	0	450,000
Repayment of short-term debt	0	0	(675,000)
Withholding remittance – share-based compensation	(3,064)	(2,199)	(1,776)
Other, including principal payments on finance leases	(2,869)	(1,771)	(1,725)
Net cash used in financing activities	(75,142)	(181,970)	398,358
Change in cash and cash equivalents, including discontinued operations	(254,665)	239,919	19,331
Cash and cash equivalents, including discontinued operations, at beginning of period	311,073	71,154	51,823
Cash and cash equivalents, including discontinued operations, at end of period	56,408	311,073	71,154
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	176,958	156,998	139,747
Increase (decrease) of capital expenditures in Accounts payable or Other current liabilities	25,800	(6,100)	(20,900)
Equity AFUDC capitalized in regulated operations plant	5,809	6,597	1,869
Southwest Gas Corporation \| Nonrelated Party
Changes in current assets and liabilities:
Accounts receivable, net of allowances	30,322	68,348	(35,114)
Southwest Gas Corporation \| Related Party
Changes in current assets and liabilities:
Accounts receivable, net of allowances	$ (105,550)	$ 0	$ 2,130

Income Taxes - Schedule of Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
U.S. federal statutory income tax						$ 69,483	$ 53,369	$ 35,575
State and local income tax, net of deferred benefit						40,515	3,230	9,420
Tax credits						(2,213)	(1,716)	(440)
Changes in valuation allowance						0	1,032	0
Corporate-owned life insurance						(2,242)	(1,842)	(2,196)
Other						848	589	197
Changes in unrecognized tax benefits						(182)	(1,849)	(23)
Amortization of excess deferred taxes						(10,172)	(19,656)	(23,112)
MountainWest sale						0	0	9,989
Total income tax expense		$ 79,865		$ 107,534		$ 96,037	$ 33,157	$ 29,410
Percent
U.S. federal statutory income tax						21.00%	21.00%	21.00%
State and local income tax, net of deferred benefit						12.20%	1.20%	5.60%
Tax credits						(0.60%)	(0.70%)	(0.30%)
Changes in valuation allowance						0.00%	0.40%	0.00%
Corporate-owned life insurance						(0.70%)	(0.70%)	(1.30%)
Other						0.30%	0.20%	0.10%
Changes in unrecognized tax benefits						(0.10%)	(0.70%)	0.00%
Amortization of excess deferred taxes						(0.031)	(0.077)	(0.136)
MountainWest sale						0.00%	0.00%	5.90%
Total income tax expense and effective income tax rate						29.00%	13.00%	17.40%
Southwest Gas Corporation
Amount
U.S. federal statutory income tax						$ 74,157	$ 64,001	$ 56,821
State and local income tax, net of deferred benefit						(7,298)	2,946	10,773
Tax credits						(2,213)	(1,716)	(440)
Nontaxable and nondeductible items						(1,470)	(1,057)	(2,100)
Changes in unrecognized tax benefits						(182)	(1,849)	(23)
Amortization of excess deferred taxes						(10,171)	(19,656)	(22,869)
Total income tax expense	$ (1,245)	$ (7,235)	$ 39,155	$ 31,920	$ 30,675	$ 52,823	$ 42,669	$ 42,162
Percent
U.S. federal statutory income tax						21.00%	21.00%	21.00%
State and local income tax, net of deferred benefit						(2.10%)	1.00%	4.00%
Tax credits						(0.60%)	(0.60%)	(0.20%)
Nontaxable and nondeductible items						(0.30%)	(0.30%)	(0.70%)
Changes in unrecognized tax benefits						(0.10%)	(0.60%)	0.00%
Amortization of excess deferred taxes						(0.029)	(0.065)	(0.085)
Total income tax expense and effective income tax rate						15.00%	14.00%	15.60%

Cover - USD ($)

12 Months Ended

Dec. 31, 2025

Feb. 18, 2026

Jun. 30, 2025

Entity Information [Line Items]

Document Type

10-K

Document Annual Report

true

Document Period End Date

Dec. 31, 2025

--12-31

Document Transition Report

false

Entity File Number

001-37976

Entity Registrant Name

Southwest Gas Holdings, Inc.

Entity Incorporation, State or Country Code

Entity Tax Identification Number

81-3881866

Entity Address, Address Line One

8360 S. Durango Dr.

Entity Address, City or Town

Las Vegas,

Entity Address, State or Province

Entity Address, Postal Zip Code

89113

City Area Code

(702)

Local Phone Number

876-7237

Title of 12(b) Security

Southwest Gas Holdings, Inc. Common Stock, $1 par value

Trading Symbol

SWX

Security Exchange Name

NYSE

Entity Well-known Seasoned Issuer

Yes

Entity Voluntary Filers

Entity Current Reporting Status

Yes

Entity Interactive Data Current

Yes

Entity Filer Category

Large Accelerated Filer

Entity Small Business

false

Entity Emerging Growth Company

false

ICFR Auditor Attestation Flag

true

Document Financial Statement Error Correction

false

Entity Shell Company

false

Entity Public Float

$ 5,354,455,918

Entity Common Stock, Shares Outstanding

72,269,125

Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE


Description						Part Into Which Incorporated
2026 Proxy Statement						Part III

Entity Central Index Key

0001692115

Document Fiscal Year Focus

2025

Document Fiscal Period Focus

Amendment Flag

false

Southwest Gas Corporation

Entity Information [Line Items]

Document Type

10-K

Document Annual Report

true

Document Period End Date

Dec. 31, 2025

Current Fiscal Year End Date

--12-31

Document Transition Report

false

Entity File Number

1-7850

Entity Registrant Name

Southwest Gas Corporation

Entity Incorporation, State or Country Code

Entity Tax Identification Number

88-0085720

Entity Address, Address Line One

8360 S. Durango Dr.

Entity Address, City or Town

Las Vegas,

Entity Address, State or Province

Entity Address, Postal Zip Code

89113

City Area Code

(702)

Local Phone Number

876-7237

Entity Well-known Seasoned Issuer

Entity Voluntary Filers

Entity Current Reporting Status

Yes

Entity Interactive Data Current

Yes

Entity Filer Category

Non-accelerated Filer

Entity Small Business

false

Entity Emerging Growth Company

false

ICFR Auditor Attestation Flag

false

Document Financial Statement Error Correction

false

Entity Shell Company

false

Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE


Description						Part Into Which Incorporated
2026 Proxy Statement						Part III

Entity Central Index Key

0000092416

Document Fiscal Year Focus

2025

Document Fiscal Period Focus

Amendment Flag

false

Dispositions - Schedule of Net Proceeds from Sale of Stock (Details) - USD ($) $ in Millions						3 Months Ended
	Sep. 05, 2025	Aug. 11, 2025	Jul. 08, 2025	Jun. 18, 2025	May 22, 2025	Sep. 05, 2025
Public Offering And Private Placement
Subsidiary or Equity Method Investee [Line Items]
Net proceeds from sale of stock		$ 355.2			$ 224.6	$ 1,349.9
Public Offering
Subsidiary or Equity Method Investee [Line Items]
Net proceeds from sale of stock	$ 524.0			$ 224.1
Private Placement
Subsidiary or Equity Method Investee [Line Items]
Net proceeds from sale of stock			$ 22.0

Previously Issued Condensed Consolidated Financial Statements (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Changes and Error Corrections [Abstract]

Schedule of Error Corrections and Prior Period Adjustments

The effects of the correction of the errors on the Consolidated Financial Statements are as follows:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEET
(In thousands)

	December 31, 2024
	As Reported(1)		Adjustments		As Revised
ASSETS


Accounts receivable, net of allowance	$	202,947	$	(2,100)	$	200,847



Total current assets	859,055		(2,100)		856,955
Total assets	$	9,533,825	$	(2,100)	$	9,531,725
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,096,149	$	(36,376)	$	1,059,773
Total equity	3,271,862		(36,376)		3,235,486
Total capitalization	6,776,339		(36,376)		6,739,963
Accounts payable	190,612		1,997		192,609
Deferred purchased gas costs	255,398		(1,997)		253,401


Total current liabilities	769,026		—		769,026
Deferred income taxes and investment tax credits, net	819,973		34,276		854,249

Total deferred income taxes and other credits	1,988,460		34,276		2,022,736
Total capitalization and liabilities	$	9,533,825	$	(2,100)	$	9,531,725
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,475,216	$	7,774	$	2,482,990
Net cost of gas sold	1,150,005		7,359		1,157,364
Total operating expenses	2,062,885		7,359		2,070,244
Operating income	412,331		415		412,746
Income before income taxes	304,350		415		304,765
Income tax expense (benefit)	43,174		(505)		42,669
Net income	$	261,176	$	920	$	262,096






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,499,564	$	(5,344)	$	2,494,220
Net cost of gas sold	1,246,901		4,466		1,251,367
Operations and maintenance	511,646		(1,259)		510,387
Total operating expenses	2,141,270		3,207		2,144,477
Operating income (loss)	358,294		(8,551)		349,743
Income (loss) before income taxes	279,125		(8,551)		270,574
Income tax expense	36,899		5,263		42,162
Net income (loss)	$	242,226	$	(13,814)	$	228,412


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Net income	$	261,176	$	920	$	262,096
Comprehensive income	$	263,323	$	920	$	264,243






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Comprehensive income (loss)	$	239,939	$	(13,814)	$	226,125


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)

	Year Ended December 31, 2024
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	261,176	$	920	$	262,096
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	69,459		(505)		68,954
Changes in current assets and liabilities:
Accounts receivable, net of allowances	66,248		2,100		68,348
Deferred purchased gas costs	706,896		8,062		714,958
Accounts payable	(19,032)		(703)		(19,735)
Other current assets and liabilities	(57,917)		(9,874)		(67,791)
Net cash provided by operating activities	$	1,252,982	$	—	$	1,252,982
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.






	Year Ended December 31, 2023
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	66,611		5,263		71,874
Changes in current assets and liabilities:
Deferred purchased gas costs	192,182		(3,956)		188,226
Accounts payable	(260,403)		7,164		(253,239)
Other current assets and liabilities	14,516		5,343		19,859


Net cash provided by operating activities	$	391,545	$	—	$	391,545
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)

	As Reported		Adjustments		As Revised
Retained earnings, December 31, 2022	$	935,355	$	(23,482)	$	911,873
Total equity, December 31, 2022	2,569,175		(23,482)		2,545,693
Net income (loss) for the year ended December 31, 2023	242,226		(13,814)		228,412
Retained earnings, December 31, 2023	1,018,474		(37,296)		981,178
Total equity, December 31, 2023	3,183,615		(37,296)		3,146,319
Net income for the year ended December 31, 2024	261,176		920		262,096
Retained earnings, December 31, 2024	1,096,149		(36,376)		1,059,773
Total equity, December 31, 2024	$	3,271,862	$	(36,376)	$	3,235,486

The effects of the Company’s prior-period errors on our Condensed Consolidated Financial Statements are as follows:


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	June 30, 2025
	As Reported		Adjustments		As Restated(1)






















CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	769,723	$	(27,271)	$	742,452
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,674,657		(27,271)		3,647,386

Total equity	4,115,805		(27,271)		4,088,534


Total capitalization	8,520,371		(27,271)		8,493,100













Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	927,486		27,271		954,757



Total deferred income taxes and other credits	2,279,069		27,271		2,306,340
Total capitalization and liabilities	$	12,213,945	$	—	$	12,213,945

(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	September 30, 2025
	As Reported		Adjustments		As Restated
























CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	999,399	$	(35,113)	$	964,286
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,928,679		(35,113)		3,893,566

Total equity	3,928,679		(35,113)		3,893,566

Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	7,435,799		(110,113)		7,325,686
Current liabilities:
Current maturities of long-term debt	—		75,000		75,000










Total current liabilities	804,703		75,000		879,703
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	905,604		35,113		940,717



Total deferred income taxes and other credits	2,088,077		35,113		2,123,190
Total capitalization and liabilities	$	10,328,579	$	—	$	10,328,579


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
(In thousands, except per share amounts)
(Unaudited)


	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated(1)		As Reported		Adjustments		As Restated(1)

















Income tax expense (benefit)	$	52,594	$	27,271	$	79,865	$	80,263	$	27,271	$	107,534


Net income (loss)	(10,329)		(27,271)		(37,600)		98,858		(27,271)		71,587

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	(12,883)	$	(27,271)	$	(40,154)	$	100,987	$	(27,271)	$	73,716

Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.:


Basic	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02




Diluted	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02

Weighted average shares:
Basic	72,088				72,088		72,050				72,050
Diluted	72,088				72,088		72,195				72,195
(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated















Income tax expense (benefit)	$	(803)	$	7,842	$	7,039	$	36,059	$	35,113	$	71,172
Income (loss) from continuing operations	4,175		(7,842)		(3,667)		165,003		(35,113)		129,890

Net income (loss)	267,959		(7,842)		260,117		366,817		(35,113)		331,704

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	270,476	$	(7,842)	$	262,634	$	371,463	$	(35,113)	$	336,350

Basic earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.29	$	(0.49)	$	1.80

Net earnings (loss) per share - basic	$	3.75	$	(0.11)	$	3.64	$	5.15	$	(0.49)	$	4.66

Diluted earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.28	$	(0.49)	$	1.79

Net earnings (loss) per share - diluted	$	3.74	$	(0.11)	$	3.63	$	5.14	$	(0.49)	$	4.65

Weighted average shares:
Basic	72,209				72,209		72,104				72,104
Diluted	72,405				72,405		72,265				72,265


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	(10,329)	$	(27,271)	$	(37,600)	$	98,858	$	(27,271)	$	71,587









Comprehensive income (loss)	(3,351)		(27,271)		(30,622)		106,208		(27,271)		78,937

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	(6,970)	$	(27,271)	$	(34,241)	$	107,252	$	(27,271)	$	79,981






	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	267,959	$	(7,842)	$	260,117	$	366,817	$	(35,113)	$	331,704









Comprehensive income (loss)	266,566		(7,842)		258,724		372,774		(35,113)		337,661

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	269,879	$	(7,842)	$	262,037	$	377,131	$	(35,113)	$	342,018


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	98,858	$	(27,271)	$	71,587


Adjustments to reconcile net income (loss) to net cash provided by operating activities:

Deferred income taxes	94,033		27,271		121,304
Net cash provided by operating activities	$	417,611	$	—	$	417,611


	Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	366,817	$	(35,113)	$	331,704

Income (loss) from continuing operations, net of income tax	165,003		(35,113)		129,890
Adjustments to reconcile net income to net cash provided by operating activities:

Deferred income taxes	48,141		35,113		83,254
Net cash provided by operating activities of continuing operations	509,136		—		509,136

Net cash provided by operating activities	$	474,508	$	—	$	474,508


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Restated


Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended June 30, 2025	$	(12,883)	$	(27,271)	$	(40,154)
Retained earnings, June 30, 2025	769,723		(27,271)		742,452
Total equity attributable to Southwest Gas Holdings, Inc., June 30, 2025	3,674,657		(27,271)		3,647,386
Total equity, June 30, 2025	4,115,805		(27,271)		4,088,534
Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended September 30, 2025	270,476		(7,842)		262,634
Retained earnings, September 30, 2025	999,399		(35,113)		964,286
Total equity attributable to Southwest Gas Holdings, Inc., September 30, 2025	3,928,679		(35,113)		3,893,566
Total equity, September 30, 2025	$	3,928,679	$	(35,113)	$	3,893,566

The impacts of the revisions are presented in the tables below:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	March 31, 2025
	As Reported		Adjustments		As Revised



CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,238,775	$	(36,723)	$	1,202,052
Total equity	3,416,872		(36,723)		3,380,149
Total capitalization	6,922,224		(36,723)		6,885,501


Deferred income taxes and investment tax credits, net	857,986		36,723		894,709
Total deferred income taxes and other credits	2,025,235		36,723		2,061,958
Total capitalization and liabilities	$	9,679,467	$	—	$	9,679,467






	June 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,227,760	$	(24,754)	$	1,203,006
Total equity	3,408,373		(24,754)		3,383,619
Total capitalization	6,914,610		(24,754)		6,889,856


Deferred income taxes and investment tax credits, net	871,647		24,754		896,401
Total deferred income taxes and other credits	2,047,726		24,754		2,072,480
Total capitalization and liabilities	$	9,688,433	$	—	$	9,688,433






	September 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,233,196	$	(23,931)	$	1,209,265
Total equity	3,416,463		(23,931)		3,392,532
Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	6,923,583		(98,931)		6,824,652
Current maturities of long-term debt	—		75,000		75,000
Total current liabilities	751,278		75,000		826,278
Deferred income taxes and investment tax credits, net	872,344		23,931		896,275
Total deferred income taxes and other credits	2,050,616		23,931		2,074,547
Total capitalization and liabilities	$	9,725,477	$	—	$	9,725,477


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	746,416	$	2,100	$	748,516
Operating income	214,979		2,100		217,079
Income before income taxes	179,650		2,100		181,750
Income tax expense	36,708		2,447		39,155
Net income (loss)	$	142,942	$	(347)	$	142,595







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	396,318	$	—	$	396,318	$	1,142,734	$	2,100	$	1,144,834
Operating income	65,342		—		65,342		280,321		2,100		282,421
Income before income taxes	38,411		—		38,411		218,061		2,100		220,161
Income tax expense (benefit)	4,734		(11,969)		(7,235)		41,442		(9,522)		31,920
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	316,911	$	—	$	316,911	$	1,459,645	$	2,100	$	1,461,745
Operating income	37,977		—		37,977		318,298		2,100		320,398
Income before income taxes	5,098		—		5,098		223,159		2,100		225,259
Income tax expense (benefit)	(422)		(823)		(1,245)		41,020		(10,345)		30,675
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Net income (loss)	$	142,942	$	(347)	$	142,595
Comprehensive income (loss)	$	143,210	$	(347)	$	142,863







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241
Comprehensive income	$	33,944	$	11,969	$	45,913	$	177,154	$	11,622	$	188,776







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584
Comprehensive income	$	5,789	$	823	$	6,612	$	182,943	$	12,445	$	195,388


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Three Month Ended March 31, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	142,942	$	(347)	$	142,595
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	37,928		2,447		40,375
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(11,117)		(2,100)		(13,217)
Deferred purchased gas costs	53,865		1,997		55,862
Accounts payable	(44,691)		(1,997)		(46,688)
Net cash provided by operating activities	$	285,832	$	—	$	285,832







	Six Month Ended June 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	176,619	$	11,622	$	188,241
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	51,504		(9,522)		41,982
Changes in current assets and liabilities:
Accounts receivable, net of allowance	68,311		(2,100)		66,211
Deferred purchased gas costs	120,709		1,997		122,706
Accounts payable	(69,232)		(1,997)		(71,229)
Net cash provided by operating activities	$	459,287	$	—	$	459,287







	Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	182,139	$	12,445	$	194,584
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	52,890		(10,345)		42,545
Changes in current assets and liabilities:
Accounts receivable, net of allowance	92,372		(2,100)		90,272
Deferred purchased gas costs	114,768		1,997		116,765
Accounts payable	(66,237)		(1,997)		(68,234)
Net cash provided by operating activities	$	526,359	$	—	$	526,359


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Revised


Net income (loss), for the three months ended March 31, 2025	$	142,942	$	(347)	$	142,595
Retained earnings, March 31, 2025	1,238,775		(36,723)		1,202,052
Total Equity, March 31, 2025	3,416,872		(36,723)		3,380,149
Net income for the three months ended June 30, 2025	33,677		11,969		45,646
Retained earnings, June 30, 2025	1,227,760		(24,754)		1,203,006
Total Equity, June 30, 2025	3,408,373		(24,754)		3,383,619
Net income (loss) for the three months ended September 30, 2025	5,520		823		6,343
Retained earnings, September 30, 2025	1,233,196		(23,931)		1,209,265
Total Equity, September 30, 2025	$	3,416,463	$	(23,931)	$	3,392,532

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2 - Summary of Significant Accounting Policies

Basis of Presentation. The Company follows U.S. GAAP in accounting for all of its businesses. Unless specified otherwise, all amounts are in U.S. dollars. Accounting for regulated operations conforms with U.S. GAAP as applied to rate-regulated companies and as prescribed by federal agencies and commissions of the various states in which the rate-regulated companies operate. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Certain items in the prior period financial statements have been reclassified to conform to the current year presentation. Such reclassifications did not affect revenue, operating income, net income, or total cash flows from operations, investing or financing activities. These include $74.3 million and $294.9 million of changes in accrued purchased gas costs, included in the changes in other current assets and liabilities, that were reclassified to changes in deferred purchased gas costs in the Company’s and Southwest’s consolidated statements of cash flows for the years ended December 31, 2024 and 2023, respectively. See Note 3 - Revision of Previously Issued Financial Statements for the discussion of the revision to the prior year financial statements.

Discontinued Operations. On August 11, 2025, the Company completed a secondary public offering and a concurrent private placement transaction with Icahn investment entities. These transactions resulted in the sale of a combined total of 18,823,500 shares of Centuri common stock previously held by the Company (see Note 13 - Dispositions). Following the completion of these transactions, the Company no longer maintained a controlling financial interest in Centuri. Accordingly, Centuri’s assets, liabilities, and results of operations are no longer included in the Company’s consolidated financial statements.

In addition, the sale of Centuri, which comprised the Company’s Utility Infrastructure Services segment, represented a strategic shift that had a significant impact on the Company’s operations and financial results. Therefore, Centuri met the criteria to be reported as discontinued operations in accordance with U.S. GAAP. The results of discontinued operations are aggregated and presented separately in the Consolidated Statements of Income and Consolidated Statements of Cash Flows for all periods presented. Assets and liabilities of the discontinued operations are aggregated and reported separately on the Consolidated Balance Sheets as of December 31, 2024. Unless otherwise noted, the financial disclosures and related information provided herein relate to our continuing operations, which exclude our former Utility Infrastructure Services segment, and we have recast prior period amounts to reflect discontinued operations.

Consolidation. The accompanying financial statements (as of and for the periods presented) are presented on a consolidated basis for the Company and Southwest Gas. All significant intercompany balances and transactions have been eliminated with the exception of transactions between Southwest Gas and Centuri in accordance with accounting treatment for rate-regulated entities.

Fair Value Measurements. Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows:

Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date.

Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly.

Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date.

The Company primarily used quoted market prices and other observable market pricing information (exclusive of any purchase accounting adjustments) in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and the postretirement benefits other than pensions required to be recorded and/or disclosed at fair value. The Company uses prices and inputs that are current as of the measurement date and recognizes transfers between levels at either the actual date of an event or a change in circumstance that caused the transfer.

Net Regulated Operations Plant. Net regulated operations plant includes gas plant at original cost less the accumulated provision for depreciation and amortization plus any unamortized balance of acquisition adjustments. Original cost generally includes contracted services, material, payroll, and related costs such as taxes and certain benefits, general and administrative expenses applicable to construction efforts, and an allowance for funds used during construction less contributions in aid of construction. Aligned with regulatory treatment, when plant is retired the cost of such plant, net of any salvage value, is charged to accumulated depreciation. See also Depreciation and Amortization below.

Other Property and Investments. Other property and investments on Southwest Gas’ and the Company’s Consolidated Balance Sheets include:


	December 31,
(Thousands of dollars)	2025		2024
Net cash surrender value of COLI policies	$	165,551	$	155,199
Other property	4,396		4,479
Total Southwest Gas Corporation	169,947		159,678


Other property and investments	8,879		5,770
Total Southwest Gas Holdings, Inc.	$	178,826	$	165,448

Included in the table above are the net cash surrender values of COLI policies. These life insurance policies on members of management and other key employees are used by Southwest Gas to indemnify itself against the loss of talent, expertise, and knowledge, as well as to provide indirect funding for certain nonqualified benefit plans.

Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand, money market funds, and financial instruments with original maturities of three months or less. Such investments are carried at cost, which approximates fair value. Cash and cash equivalents of the Company include $250.5 million and $64.3 million of money market fund investments at December 31, 2025 and 2024, respectively. Of these amounts, $34.4 million and $48.8 million at December 31, 2025 and 2024, respectively, were held by Southwest Gas. The money market fund investments were acquired and are generally redeemable at their net asset value.

Income Taxes. The asset and liability method of accounting is utilized for the recognition of income taxes. Under the asset and liability method, deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the years in which those temporary differences are anticipated to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in income tax rates is recognized in the period that includes the enactment date. For regulatory and financial reporting purposes, ITCs related to gas utility operations are deferred and amortized over the life of related fixed assets.

Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable Southwest Gas to adjust billing rates for changes in the cost of natural gas purchased. The difference between the current cost of gas purchased and the cost of gas recovered in billed rates is deferred. Generally, these deferred amounts are recovered or refunded within one year.

Materials, supplies, and gas inventories. Materials, supplies, and gas inventories for Southwest Gas and the Company includes gas pipe materials and operating supplies of $78.1 million and $77.8 million as of December 31, 2025 and 2024, respectively (carried at weighted average cost).

Prepaid and other current assets. Prepaid and other current assets for Southwest Gas and the Company include, among other things, $91.1 million and $32.4 million related to a regulatory asset associated with the Arizona decoupling mechanism as of December 31, 2025 and 2024, respectively. Additionally, included in the balance for the Company is prepaid insurance premiums of $35.4 million and $25.3 million as of December 31, 2025 and 2024, respectively, and $33.9 million and $25.2 million as of December 31, 2025 and 2024, respectively, at Southwest Gas.

Goodwill. As required by U.S. GAAP, goodwill is assessed for impairment annually or more frequently if circumstances indicate impairment to the carrying value of goodwill may have occurred. The goodwill impairment analysis was conducted as of October 1, 2025 using a qualitative assessment, as permitted by U.S. GAAP. Management of the Company and Southwest Gas evaluated its reporting unit and operating segment and concluded that, following the sale of the of the Utility Infrastructure Services segment (Centuri), the Company operates solely within the Natural Gas Distribution segment (Southwest Gas); see Note 16 - Segment Information. The Company and Southwest Gas determined that it is more likely than not that the fair value of Southwest Gas’ reporting unit exceeds their carrying amounts in both 2025 and 2024 and therefore no quantitative assessment was performed.

Deferred charges and other assets. Deferred charges and other assets for Southwest Gas and the Company include, among other things, cloud-based software of $33.9 million and $24.8 million as of December 31, 2025 and 2024, respectively, and a regulatory asset associated with pension for Arizona and Nevada of $246.4 million and $300.0 million as of December 31, 2025 and 2024, respectively. The change is due to the net actuarial gain (refer to Note 10 - Pension and Other Postretirement Benefits).

Noncontrolling Interest. In connection with the Centuri IPO, the Company recorded a noncontrolling interest as part of equity in the Consolidated Balance Sheet (associated with the interests held by the new investors in Centuri) and recognized the excess of the fair value of the Centuri IPO proceeds over the carrying value of the noncontrolling interest, in addition to a portion of AOCI relevant to the proportional interest of the noncontrolling parties in Centuri, within Additional paid-in capital. The Consolidated Statements of Income include multiple components of comprehensive income attributable to noncontrolling interests following the Centuri IPO. These amounts, including those distinguishable from net income attributed to these parties, are separately presented in the Consolidated Statements of Equity. Following the completion of the Centuri Separation (see Note 13 - Dispositions below), the Company no longer maintained a controlling financial interest in Centuri. Accordingly, the noncontrolling interests in Centuri are no longer included in the Company’s consolidated financial statements.

Redeemable Noncontrolling Interest. Separate from the noncontrolling ownership interest in Centuri, redeemable noncontrolling interests have been established in association with certain business acquisitions by Centuri. Following the completion of the Centuri Separation (see Note 13 - Dispositions below), the Company no longer maintained a controlling financial interest in Centuri. Accordingly, the redeemable noncontrolling interests in Centuri are no longer included in the Company’s consolidated financial statements.

Other Current Liabilities. Management recognizes in its balance sheets various liabilities that are expected to be settled through future cash payments within the next twelve months, including certain regulatory mechanisms (refer to Note 5 - Regulatory Assets and Liabilities), customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities.

Accumulated Removal Costs. Approved regulatory practices allow Southwest Gas to include in depreciation expense a component intended to recover removal costs associated with regulated operations plant retirements. In accordance with the SEC position on presentation of these amounts, management reclassifies estimated removal costs from Accumulated depreciation to Accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Management regularly updates the estimated accumulated removal costs as amounts fluctuate between periods depending on the level of replacement work performed (and actual cost experience) compared to the estimated cost of removal in rates.

Revenue. See Note 6 - Revenue for information related to revenue recognition for Southwest Gas.

Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest Gas (see Note 16 - Segment Information). The accounts receivable balance, revenues, and associated profits were included in the consolidated financial statements of the Company and Southwest Gas and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities through the period prior to deconsolidation (see Note 13 - Dispositions).

Net Cost of Gas Sold. Components of net cost of gas sold include natural gas commodity costs (fixed-price and variable-rate), pipeline capacity/transportation costs, and any actual settled costs of natural gas derivative instruments, where relevant. Also included are the net impacts of PGA deferrals and recoveries which by their inclusion result in net cost of gas sold overall that is comparable to amounts included in billed gas operating revenues. Differences between amounts incurred with suppliers, transmission pipelines, etc. and amounts already included in customer rates are temporarily deferred in PGA accounts pending inclusion in customer rates.

Operations and Maintenance Expense. Operations and maintenance expense includes, Southwest Gas’ operating and maintenance costs associated with serving utility customers and maintaining its distribution and transmission systems, uncollectible customer accounts expense, administrative and general salaries and expense, and employee benefits expense excluding relevant non-service cost components (that have been reclassified to Other income (deductions) due to requirements in U.S. GAAP), as well as legal expenses (including injuries and damages), professional and other external contracted services, and other business expenses.

Depreciation and Amortization. Regulated operations plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which compensate for removal costs (net of salvage value), and retirements, as approved by the appropriate regulatory agency. When plant is retired from service, the original cost of plant, including cost of removal, less salvage, is charged to the accumulated provision for depreciation. See also discussion regarding Accumulated Removal Costs above. Other regulatory assets, including acquisition adjustments, are amortized, when appropriate, over time periods authorized by regulators. Costs and gains related to refunding regulated operations debt and debt issuance expenses are deferred and amortized over the weighted-average lives of the new issues and become a component of interest expense.

AFUDC. AFUDC represents the cost of both debt and equity funds used to finance regulated operations plant construction. AFUDC is capitalized as part of the cost of regulated operations plant. The debt portion of AFUDC is reported in the Company’s and Southwest Gas’ Consolidated Statements of Income as an offset to Net interest deductions and the equity portion is reported as Other income. Regulated operations plant construction costs, including AFUDC, are recoverable as part of authorized rates through depreciation when completed projects are placed into operation and general rate relief is requested and granted. AFUDC, disaggregated by type, included in the Company’s and Southwest Gas’ Consolidated Statements of Income are presented in the table below:


(Thousands of dollars)	2025			2024			2023
AFUDC:
Debt portion	$	2,707		$	3,126		$	6,851
Equity portion(1)	5,809			6,597			1,951
AFUDC capitalized as part of regulated operations plant	$	8,516		$	9,723		$	8,802
AFUDC rate	6.77		%	6.76		%	6.30		%

(1)Equity AFUDC for the year ended December 31, 2023 includes MountainWest activity.

Debt and equity AFUDC at Southwest Gas were impacted in 2023 by the amount of short-term debt outstanding based on the regulatory formula for each component.

Other Income (Deductions). The following table provides the composition of significant items included in Other income (deductions) on the Consolidated Statements of Income:


(Thousands of dollars)	2025		2024		2023
Southwest Gas Corporation:
Change in COLI policies	$	10,300	$	8,400	$	10,100
Interest income	20,944		33,581		50,757
Equity AFUDC	5,809		6,597		1,869
Non-service components of net periodic benefit cost	17,475		16,523		20,387
Miscellaneous expense	(2,126)		(10,825)		(12,452)
Southwest Gas Corporation – total other income (deductions)	52,402		54,276		70,661
Southwest Gas Holdings, Inc.:
Equity AFUDC	—		—		82
Equity in earnings of unconsolidated investments	—		—		394
Miscellaneous income and (expense)	—		—		(49)
Corporate and administrative	7,666		(84)		151
Southwest Gas Holdings, Inc. - total other income (deductions)	$	60,068	$	54,192	$	71,239

Included in the table above is the change in COLI policies (including net death benefits recognized, where relevant). Current tax regulations provide for tax-free treatment of life insurance (death benefit) proceeds. Therefore, changes in the cash surrender value components of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences.

For 2025, interest income relates to interest income earned on money market investments and interest income earned on Southwest Gas’ regulatory asset balances, including the Arizona decoupling mechanism. For 2023 and 2024, interest income primarily relates to Southwest Gas’ regulatory asset balances, including its deferred purchased gas cost mechanisms, the combined balance of which was a net asset balance of $465.3 million as of December 31, 2023 and transitioned to a net liability balance of $241.6 million as of December 31, 2024. Interest income is earned on asset balances and interest expense is incurred on liability balances. Interest earned on money market accounts, as discussed in the cash and cash equivalent section above, also contributes to interest income. In regard to net periodic benefit cost, refer to Note 10 - Pension and Other Postretirement Benefits. Miscellaneous expense for Southwest Gas between years includes a variety of items, not limited to, but including where applicable, write-offs for uncompleted software projects and the reduction in value of Southwest Gas’ previous corporate campus property.

Derivatives. In managing its natural gas supply portfolios, Southwest Gas has historically entered into fixed- and variable-price contracts, which qualify as derivatives. The fixed-price contracts, firm commitments to purchase a fixed amount of gas in the future at a fixed price, qualify for the normal purchases and normal sales exception that is allowed for contracts that are probable of delivery in the normal course of business and are exempt from fair value reporting. The variable‑price contracts meet the definition of derivative financial instruments; however, because the contract price is set at the prevailing market price on the future transaction date, no mark‑to‑market adjustment is required. Southwest Gas does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations.

EPS. Basic EPS in each period of this report were calculated by dividing net income (loss) attributable to the Company by the weighted-average number of shares during those periods. Diluted EPS includes additional weighted-average common stock equivalents (performance share units and restricted stock units), if dilutive. Unless otherwise noted, the term EPS refers to Basic EPS. A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table:


(In thousands)	2025	2024	2023
Weighted average basic shares	72,162	71,841	70,787
Effect of dilutive securities:
Restricted stock units (1)(2)	175	191	203
Weighted average diluted shares	72,337	72,032	70,990

(1) The number of securities granted for 2025, 2024, and 2023 includes 146,000, 158,000, and 173,000 performance stock units, respectively, the total of which was derived by assuming that target performance will be achieved during the relevant performance period.

(2) The number of anti-dilutive restricted stock units excluded from the calculation of diluted shares from discontinued operations in 2024 is 191,000.

Recent Accounting Standards Updates.

Recently issued accounting pronouncement adopted in 2025:

In December 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” The update, among other amendments, provides for additional disclosure requirements related to the effective income tax rate reconciliation and income taxes paid. Under the revised guidance for the effective income tax reconciliations, entities would be required to disclose: (1) eight specific categories in the effective income tax rate reconciliation in both percentages and reporting currency amount, (2) additional information for reconciling items over a certain threshold, (3) explanation of individual reconciling items disclosed, and (4) provide a qualitative description of the state and local jurisdictions that contribute to the majority of the state income tax expense. For each annual period presented, the new standard requires disclosure of the year-to-date amount of income taxes paid (net of refunds received) disaggregated by federal, state, and foreign. It also requires additional disaggregated information on income taxes paid (net of refunds received) to an individual jurisdiction equal to or greater than 5% of total income taxes paid (net of refunds received). The standard is effective for annual periods beginning January 1, 2025. The Company and Southwest Gas have retrospectively adopted this update in the fourth quarter of 2025, the impact of which is reflected in Note 11 - Income Taxes, with no impact on results of operations, cash flows, or financial condition of the Company or Southwest Gas.

In July 2025, the FASB issued ASU 2025-05 “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets.” The amendments in this update provide a practical expedient permitting an entity to assume that conditions at the balance sheet date remain unchanged over the life of the asset when estimating expected credit losses for current accounts receivable and current contract assets. The update is effective for annual periods beginning after December 15, 2025; early adoption is permitted. Management adopted ASU 2025-05 beginning with the fourth quarter of fiscal 2025 and utilized the practical expedient provided therein. The adoption of this ASU did not have a material impact on the Company’s or Southwest Gas’ financial position or results of operations.

Recently issued accounting pronouncements that will be effective in 2026 and thereafter:

In November 2024, the FASB issued ASU 2024-03 “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” The update requires disclosure of disaggregated information about certain income statement expense line items in the notes to the financial statements. The update is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027; early adoption is permitted. The update should be applied prospectively; however, retrospective application is also permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest Gas’ disclosures.

In September 2025, the FASB issued ASU 2025-06 “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software.” The amendments in this update improve the operability of the guidance by removing all references to software development project stages so that the guidance is neutral to different software development methods. This update is effective for annual periods beginning after December 15, 2027, including interim periods within those fiscal years; early adoption is permitted. Management is evaluating the impacts this update might have on the Company’s and Southwest Gas’ consolidated financial statements.

Subsequent Events. Management monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made and has reflected them where appropriate.

Pension and Other Postretirement Benefits - Schedule of Amounts Recognized in Balance Sheet and Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Change in plan assets:
Market value of plan assets at beginning of year	$ 1,158,394
Market value of plan assets at end of year	1,267,047	$ 1,158,394
QRP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	1,175,245	1,241,177
Service cost	24,394	28,252	$ 25,840
Interest cost	65,588	60,387	59,165
Actuarial loss (gain)	2,877	(87,575)
Benefits paid	(69,232)	(66,996)
Benefit obligation at end of year (PBO/PBO/APBO)	1,198,872	1,175,245	1,241,177
Change in plan assets:
Market value of plan assets at beginning of year	1,120,272	1,166,372
Actual return on plan assets	148,883	896
Employer contributions	25,000	20,000
Benefits paid	(69,232)	(66,996)
Market value of plan assets at end of year	1,224,923	1,120,272	1,166,372
Funded status at year end	$ 26,051	$ (54,973)
Weighted-average assumptions (benefit obligation):
Discount rate	5.75%	5.75%
Weighted-average rate of compensation increase	3.50%	3.50%
SERP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$ 43,183	$ 45,031
Service cost	231	243	250
Interest cost	2,383	2,167	2,123
Actuarial loss (gain)	2,464	(725)
Benefits paid	(3,688)	(3,533)
Benefit obligation at end of year (PBO/PBO/APBO)	44,573	43,183	45,031
Change in plan assets:
Market value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	3,688	3,533
Benefits paid	(3,688)	(3,533)
Market value of plan assets at end of year	0	0	0
Funded status at year end	$ (44,573)	$ (43,183)
Weighted-average assumptions (benefit obligation):
Discount rate	5.50%	5.75%
Weighted-average rate of compensation increase	3.50%	3.50%
PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$ 62,064	$ 66,009
Service cost	1,168	1,287	1,269
Interest cost	3,426	3,178	3,302
Actuarial loss (gain)	1,418	(2,691)
Benefits paid	(4,897)	(5,719)
Benefit obligation at end of year (PBO/PBO/APBO)	63,179	62,064	66,009
Change in plan assets:
Market value of plan assets at beginning of year	38,122	35,920
Actual return on plan assets	5,337	3,027
Employer contributions	0	2,514
Benefits paid	(1,335)	(3,339)
Market value of plan assets at end of year	42,124	38,122	$ 35,920
Funded status at year end	$ (21,055)	$ (23,942)
Weighted-average assumptions (benefit obligation):
Discount rate	5.50%	5.75%

Background and Organization (Details) $ in Billions	1 Months Ended	12 Months Ended	30 Months Ended
Background and Organization (Details) $ in Billions	Feb. 28, 2023 segment	Dec. 31, 2025 segment	Aug. 31, 2025 segment	Aug. 01, 2025	Apr. 30, 2024	Feb. 14, 2023 USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments \| segment	3	1	2
Centuri Holdings, Inc.
Significant Accounting Policies [Line Items]
Ownership percentage by parent				52.10%	81.00%
Discontinued Operations, Disposed of by Sale \| MountainWest
Significant Accounting Policies [Line Items]
Ownership percentage disposed						100.00%
Discontinued operation, consideration \| $						$ 1.5

Revenue

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Revenue

Note 6 - Revenue

Southwest Gas recognizes revenue when it satisfies its performance by transferring gas to the customer. Revenues also include the net impacts of margin tracker and decoupling accruals based on criteria in U.S. GAAP for rate-regulated entities associated with alternative revenue programs. Revenues from customer arrangements and from alternative revenue programs are described below.

Southwest Gas acts as an agent for state and local taxing authorities in the collection and remittance of a variety of taxes, including sales and use taxes and surcharges. These taxes are not included in Regulated operations revenues. Management uses the net classification method to report taxes collected from customers to be remitted to governmental authorities.

Southwest Gas generally offers two types of services to its customers: tariff sales and transportation–only service. Tariff sales encompass sales to primarily residential and small commercial customers under various rate schedules, subject to cost-of-service ratemaking, which is based on the rate-regulation of the ACC, CPUC, PUCN, and FERC. Southwest Gas provides both the commodity and the related distribution service to nearly all of its approximate 2.3 million customers, and only several hundred customers subscribe to transportation-only service. Natural gas is delivered and consumed by the customer simultaneously. The provision of service is represented by the turn of the meter dial and is the primary representation of the satisfaction of all performance obligations required for Southwest Gas to recognize revenue. The amount billable via regulated rates, billed via both volumetric and fixed monthly rates as part of rate design, corresponds to the value to the customer, and Southwest Gas believes that the amount billable is appropriate to utilize for purposes of recognizing revenue. Estimated amounts remaining unbilled since the last meter read date are also recognized for service provided through the balance sheet date. While natural gas service is typically recurring, there is generally not a contract term for utility service. Therefore, the contract term is not generally viewed to extend beyond the service provided to date and customers are able to generally terminate service at will.

Transportation-only service is also governed by tariff rate provisions. Transportation-only service is generally only available to large customers under requirements of Southwest Gas’ various tariffs. With this service, customers secure their own gas supply and Southwest Gas provides transportation services to move the customer-supplied gas to the intended location. Southwest Gas recognizes transportation service revenue over time through a combination of volumetric charges and fixed charges through a variety of design mechanisms approved by regulators. These types of fixed charges represent a separate performance obligation associated with standing ready over the period of the month to deliver quantities of gas regardless of whether the customer takes delivery of any quantity of gas. The performance obligations under these circumstances are satisfied over the course of the month under an output measure of progress based on time, which correlates to the period for which the charges are eligible to be invoiced.

Under its regulations, Southwest Gas enters into negotiated-rate contracts with customers located near competing pipelines that pose a risk of bypassing its distribution system. Southwest Gas may also enter into similar contracts for customers that are otherwise able to satisfy their energy needs through a fuel alternative to natural gas. Less than two dozen customers are party to contracts with rate components subject to negotiation. Many rate provisions and terms of service for these less common types of contracts are also subject to regulatory oversight and tariff provisions. The performance obligations for these customers are satisfied similarly to those for other customers by means of transporting and delivering natural gas to the customer. Many or most of the rate components and structures for these types of customers are the same as those for similar customers that do not have without negotiated rate components and the negotiated rates are within the parameters of the tariff guidelines. Furthermore, while some of these contracts may include multi-year contract periods because amounts billable under the contract are based on rates in effect for the customer for service provided to date, no significant financing component is believed to exist.

As indicated above, revenues also include the net impacts of margin tracker and decoupling accruals. All of Southwest Gas’ service territories have decoupled rate structures that are designed to eliminate the direct link between volumetric sales and revenue, thereby mitigating the impacts of unusual weather variability and conservation on margin. These decoupled rate structures qualify as alternative revenue programs. The primary alternative revenue programs involve adjustments for differences between stated tariff benchmarks and amounts billed through revenue from contracts with customers via existing rates. Such adjustments are recognized monthly in revenue and in the associated regulatory asset or liability accounts in advance of rate adjustments intended to collect or return the amounts recognized. Revenues recognized for the adjustment to the benchmarks noted are required to be presented separately from revenues from contracts with customers, as such, these revenues are disaggregated in the table below as Alternative revenue program revenues.

Southwest Gas’ operating revenues, but not its operating margin, are directly impacted by variability between comparative periods in the cost of natural gas procured for customers as these costs are incorporated in customer rates. When included in rates (for customers except those taking transportation-only service), these costs are passed through to customers generally dollar-for-dollar without markup. Operating margin is a non-GAAP financial measure and should be considered in addition to, not as a substitute for, measures of financial performance prepared in accordance with GAAP. Southwest Gas’ revenues overall, reflected on the Consolidated Statements of Income of both the Company and Southwest Gas, include revenue from contracts with customers, which is shown below disaggregated by customer type, in addition to other categories of revenue:


	December 31,
(Thousands of dollars)	2025		2024		2023
Residential	$	1,276,677	$	1,654,685	$	1,725,223
Small commercial	333,408		493,709		513,366
Large commercial	72,367		111,350		117,973
Industrial and other	44,941		62,997		75,219
Transportation	116,579		115,782		104,298
Revenue from contracts with customers	1,843,972		2,438,523		2,536,079
Alternative revenue program revenues	86,593		23,055		(52,365)
Other revenues (1)	9,815		13,638		15,850
Total Regulated operations revenues (2)(3)(4)	$	1,940,380	$	2,475,216	$	2,499,564

(1) Amounts include late fees and other miscellaneous revenues and may also include the impact of certain regulatory mechanisms.

(2) The amounts differ from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(3) The Company’s Total Regulated operations revenues differ from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(4) The Company’s revenues for the period ended December 31, 2023 represent the amounts for the Natural Gas Distribution segment and do not include amounts attributable to MountainWest. As these amounts are not material, management has not provided disaggregated revenue disclosures.

As of December 31, 2025, the Company and Southwest had backlog performance obligations through Great Basin, excluding intercompany transactions, totaling $58.2 million for the next four years. Of the current backlog, $15.9 million is expected to be fulfilled within the year ended December 31, 2026. $15.9 million within the year ended December 31, 2027, $15.9 million within the year ended December 31, 2028, and $10.5 million within the year ended December 31, 2029. Under the terms of Great Basin’s current settlement agreement, new rates will become effective no later than September 1, 2029. Accordingly, the Company and Southwest Gas are unable to reasonably estimate performance obligations that may arise beyond September 1, 2029. The backlog consists of firm customer contracts for natural gas distribution services. Seasonal fluctuation may impact the timing of fulfillment as demand for natural gas typically increases during winter months. The Company defines backlog as the aggregate value of signed contracts for which performance obligations remain unsatisfied.

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Revenue from Contract with Customer [Abstract]

Revenue (Tables)

12 Months Ended

Dec. 31, 2025

Schedule of Revenue Disaggregated by Service Type and Contract Type

Southwest Gas’ revenues overall, reflected on the Consolidated Statements of Income of both the Company and Southwest Gas, include revenue from contracts with customers, which is shown below disaggregated by customer type, in addition to other categories of revenue:


	December 31,
(Thousands of dollars)	2025		2024		2023
Residential	$	1,276,677	$	1,654,685	$	1,725,223
Small commercial	333,408		493,709		513,366
Large commercial	72,367		111,350		117,973
Industrial and other	44,941		62,997		75,219
Transportation	116,579		115,782		104,298
Revenue from contracts with customers	1,843,972		2,438,523		2,536,079
Alternative revenue program revenues	86,593		23,055		(52,365)
Other revenues (1)	9,815		13,638		15,850
Total Regulated operations revenues (2)(3)(4)	$	1,940,380	$	2,475,216	$	2,499,564

(1) Amounts include late fees and other miscellaneous revenues and may also include the impact of certain regulatory mechanisms.

(2) The amounts differ from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(3) The Company’s Total Regulated operations revenues differ from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total operating revenues					$ 1,940,380	$ 2,475,216	$ 2,534,696
Net cost of gas sold					497,636	1,150,005	1,253,269
Operations and maintenance expense					544,064	526,679	533,009
Other segment items							579,014
Income from continuing operations before income taxes					330,873	254,136	169,404
Income tax expense		$ 79,865	$ 107,534		96,037	33,157	29,410
Income from continuing operations	$ (3,667)			$ 129,890	234,836	220,979	139,994
Income (loss) from discontinued operations, net of income tax					200,344	(16,143)	15,523
Net income	260,117	(37,600)	71,587	331,704	435,180	204,836	155,517
Net income attributable to noncontrolling interests					(4,646)	6,021	4,628
Net income	$ 262,634	$ (40,154)	$ 73,716	$ 336,350	439,826	198,815	150,889
Interest income							50,757
Interest expense							194,810
Depreciation and amortization					330,724	303,095	295,462
Goodwill impairment and loss on sale					0	0	71,230
Segment assets					$ 10,429,477	$ 12,072,906	9,277,306
Capital expenditures							765,871
Operating Segments
Segment Reporting Information [Line Items]
Revenues from external customers							2,571,211
Alternative revenue program and other revenues							(36,515)
Other
Segment Reporting Information [Line Items]
Net cost of gas sold							0
Operations and maintenance expense							9,985
Other segment items							92,703
Income from continuing operations before income taxes							(102,688)
Income tax expense							(16,744)
Income from continuing operations							(85,944)
Interest income							0
Interest expense							42,780
Depreciation and amortization							0
Goodwill impairment and loss on sale							50,015
Segment assets							8,735
Capital expenditures							0
Natural Gas Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Revenues from external customers							2,536,079
Alternative revenue program and other revenues							(36,515)
Total operating revenues							2,499,564
Net cost of gas sold							1,246,901
Operations and maintenance expense							511,646
Other segment items							461,892
Income from continuing operations before income taxes							279,125
Income tax expense							36,899
Income from continuing operations							242,226
Interest income							50,757
Interest expense							149,830
Depreciation and amortization							295,462
Goodwill impairment and loss on sale							0
Segment assets							9,268,571
Capital expenditures							762,081
Pipeline And Storage \| Operating Segments
Segment Reporting Information [Line Items]
Revenues from external customers							35,132
Alternative revenue program and other revenues							0
Total operating revenues							35,132
Net cost of gas sold							6,368
Operations and maintenance expense							11,378
Other segment items							24,419
Income from continuing operations before income taxes							(7,033)
Income tax expense							9,255
Income from continuing operations							(16,288)
Interest income							0
Interest expense							2,200
Depreciation and amortization							0
Goodwill impairment and loss on sale							21,215
Segment assets							0
Capital expenditures							$ 3,790

Commitments and Contingencies (Details) - Southwest Gas Corporation	Dec. 31, 2025 USD ($)
Loss Contingencies [Line Items]
Self-insured retention amount associated with general liability claims	$ 1,000,000.0
Additional self-insured retention amount of general liability	$ 4,000,000.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Schedule of Asset Return Assumption

Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2025

Retirement Benefits [Abstract]

The rates are presented in the table below:


	December 31,
	2025		2024


Asset return assumption	7.00	%	7.00	%

Schedule of Defined Benefit Plans Disclosures

The following table sets forth the QRP, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income.


	Year Ended December 31,
	2025									2024
(Thousands of dollars)	QRP			SERP			PBOP			QRP			SERP			PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$	1,175,245		$	43,183		$	62,064		$	1,241,177		$	45,031		$	66,009
Service cost	24,394			231			1,168			28,252			243			1,287
Interest cost	65,588			2,383			3,426			60,387			2,167			3,178

Actuarial loss (gain)	2,877			2,464			1,418			(87,575)			(725)			(2,691)
Benefits paid	(69,232)			(3,688)			(4,897)			(66,996)			(3,533)			(5,719)
Benefit obligation at end of year (PBO/PBO/APBO)	1,198,872			44,573			63,179			1,175,245			43,183			62,064
Change in plan assets:
Market value of plan assets at beginning of year	1,120,272			—			38,122			1,166,372			—			35,920
Actual return on plan assets	148,883			—			5,337			896			—			3,027
Employer contributions	25,000			3,688			—			20,000			3,533			2,514
Benefits paid	(69,232)			(3,688)			(1,335)			(66,996)			(3,533)			(3,339)
Market value of plan assets at end of year	1,224,923			—			42,124			1,120,272			—			38,122
Funded status at year end	$	26,051		$	(44,573)		$	(21,055)		$	(54,973)		$	(43,183)		$	(23,942)
Weighted-average assumptions (benefit obligation):
Discount rate	5.75		%	5.50		%	5.50		%	5.75		%	5.75		%	5.75		%
Weighted-average rate of compensation increase	3.50		%	3.50		%	N/A			3.50		%	3.50		%	N/A

Schedule of Accumulated Benefit Obligation

The accumulated benefit obligation for the QRP and the SERP is presented below:


	December 31,
(Thousands of dollars)	2025		2024
QRP	$	1,091,081	$	1,084,462
SERP	42,382		40,753

Schedule of Expected Benefit Payments

Benefits expected to be paid for the QRP, SERP, and PBOP over the next 10 years are as follows:


(Millions of dollars)	2026		2027		2028		2029		2030		2031-2035
QRP	$	72.0	$	73.0	$	74.0	$	75.0	$	77.0	$	409.0
SERP	3.5		3.5		3.4		3.4		3.4		16.2
PBOP	5.0		5.1		5.1		5.1		5.2		25.8

Schedule of Net Benefit Cost

Components of net periodic benefit cost:


	2025									2024									2023
(Thousands of dollars)	QRP			SERP			PBOP			QRP			SERP			PBOP			QRP			SERP			PBOP
Service cost	$	24,394		$	231		$	1,168		$	28,252		$	243		$	1,287		$	25,840		$	250		$	1,269
Interest cost	65,588			2,383			3,426			60,387			2,167			3,178			59,165			2,123			3,302
Expected return on plan assets	(90,328)			—			(2,495)			(87,812)			—			(2,259)			(84,062)			—			(2,424)
Amortization of prior service cost	—			—			175			—			—			175			—			—			175
Amortization of net actuarial loss	3,007			1,082			(313)			6,308			1,333			—			336			998			—
Net periodic benefit cost	$	2,661		$	3,696		$	1,961		$	7,135		$	3,743		$	2,381		$	1,279		$	3,371		$	2,322
Weighted-average assumptions (net benefit cost)
Discount rate	5.75		%	5.75		%	5.75		%	5.00		%	5.00		%	5.00		%	5.25		%	5.25		%	5.25		%
Expected return on plan assets	7.00		%	N/A			7.00		%	6.75		%	N/A			6.75		%	6.75		%	N/A			6.75		%
Weighted-average rate of compensation increase	3.50		%	3.50		%	N/A			3.50		%	3.50		%	N/A			3.25		%	3.25		%	N/A

Schedule of Amounts Recognized in Other Comprehensive Income

Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income


	Year Ended December 31,
	2025								2024								2023
(Thousands of dollars)	QRP		SERP		PBOP		Total		QRP		SERP		PBOP		Total		QRP		SERP		PBOP		Total
Net actuarial loss (gain) (a)	$	(55,680)	$	2,463	$	(1,423)	$	(54,640)	$	(659)	$	(725)	$	(3,458)	$	(4,842)	$	455	$	3,995	$	(1,262)	$	3,188
Amortization of prior service cost (b)	—		—		(175)		(175)		—		—		(175)		(175)		—		—		(175)		(175)
Amortization of net actuarial loss (b)	(3,007)		(1,081)		313		(3,775)		(6,308)		(1,333)		—		(7,641)		(335)		(998)		—		(1,333)

Regulatory adjustment	52,232		—		1,285		53,517		6,200		—		3,633		9,833		(107)		—		1,437		1,330
Recognized in other comprehensive (income) loss	(6,455)		1,382		—		(5,073)		(767)		(2,058)		—		(2,825)		13		2,997		—		3,010
Net periodic benefit costs recognized in net income	2,661		3,696		1,961		8,318		7,135		3,743		2,381		13,259		1,279		3,371		2,322		6,972
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$	(3,794)	$	5,078	$	1,961	$	3,245	$	6,368	$	1,685	$	2,381	$	10,434	$	1,292	$	6,368	$	2,322	$	9,982

The table above discloses the net gain or loss and prior service cost recognized in Other comprehensive income, separated into (a) amounts initially recognized in Other comprehensive income, and (b) amounts subsequently recognized as adjustments to Other comprehensive income as those amounts are amortized as components of net periodic benefit cost.

Schedule of Fair Value of Plan Assets

The following table sets forth, by level within the three-level fair value hierarchy, the fair values of the assets of the QRP and the PBOP as of December 31, 2025 and 2024. The SERP has no assets.


	December 31,
	2025						2024
(Thousands of dollars)	QRP		PBOP		Total		QRP		PBOP		Total
Assets at fair value:
Level 2 – Significant other observable inputs
Government fixed income (1)	$	6,974	$	6	$	6,980	$	5,048	$	4	$	5,052
Total Level 2 assets	6,974		6		6,980		5,048		4		5,052
Investments measured at NAV:
Mutual funds (2)	—		40,790		40,790		—		36,951		36,951
Pooled funds and mutual funds (3)	24,289		306		24,595		15,009		191		15,200
Commingled trust equity funds (4)
Global	220,661		189		220,850		237,333		211		237,544
International	99,508		85		99,593		105,977		94		106,071
U.S. equity securities	176,970		152		177,122		171,122		153		171,275
Emerging markets	61,510		54		61,564		55,327		49		55,376
Commingled trust fixed income funds (5)	632,863		542		633,405		528,238		469		528,707
Insurance company general account contracts (6)	2,148		—		2,148		2,218		—		2,218
Total Plan assets	$	1,224,923	$	42,124	$	1,267,047	$	1,120,272	$	38,122	$	1,158,394

(1) Government fixed income consists of government-related securities including cash and cash equivalent securities as well as assets invested in the Treasury futures overlay and associated cash collateral.

(2) The Mutual funds category is a balanced fund that invests in diversified portfolios of common stocks, preferred stocks, and fixed-income securities. Under normal circumstances, the fund invests between 25% and 75% of its total assets in equity securities and at least 25% in fixed-income investments. It may also invest up to 30% in non-U.S. securities. The fund seeks regular income, conservation of principal, and an opportunity for long-term growth of principal and income.

(3) These funds are collective short-term funds that invest in Treasury bills and money market funds and are used as a temporary cash repository.

(4) The commingled trust equity funds include common collective trusts that invest in diversified portfolios of securities regularly traded on securities exchanges. These funds are shown in the above table at NAV, which is the value of securities in the fund less the amount of any liabilities outstanding. Strategies employed by the funds include investment in:

▪Global equities, including domestic (U.S.) and international equities

▪International developed countries equities

▪Domestic (U.S.) equities

▪Emerging markets equities

Shares in the commingled trust equity funds may be redeemed given one business day advance notice. The global fund provides diversified exposure to global equity markets. The fund seeks to provide long-term capital growth by investing primarily in securities listed on the major developed equity markets of the U.S., Europe, and Asia, as well as within those listed on emerging country equity markets on a tactical basis.

The international fund invests in international financial markets, primarily those of developed economies in Europe and Asia. The fund invests primarily in equity securities issued by foreign corporations but may invest in other securities perceived as offering attractive investment return opportunities.

The domestic equities securities funds include a large and medium capitalization fund and a small capitalization fund. The large and medium capitalization fund is designed to track the performance of the large and medium capitalization companies contained in the index, which represents approximately 90% of the market capitalization of the U.S. stock market. The small capitalization fund is designed to provide maximum long-term appreciation through investments that are well diversified by industry.

The emerging markets fund invests in countries defined as an emerging market country. Fund investments are made directly in each country or, where direct investment is inefficient or prohibited, through appropriate financial instruments or participation in commingled funds. Major emerging markets include Brazil, India, China, and other developing countries around the world.

(5) The commingled trust fixed income funds consist primarily of fixed income debt securities issued by the U.S. Treasury, government agencies, and fixed income debt securities issued by corporations. The fixed income fund investments may include the use of high yield international fixed income securities and other instruments, including derivatives, to ensure prudent diversification over a broad spectrum of investments. The changes in the value of the fixed income funds are intended to offset the changes in the pension plan liabilities due to changes in the discount rate.

(6) The insurance company general account contracts are annuity insurance contracts used to pay the pensions of employees who retired prior to 1989. The balance of the account disclosed in the above table is the contract value, which is the result of deposits, withdrawals, and interest credits.

Income Taxes - Schedule of Income Taxes Paid (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax [Line Items]
Federal	$ 24,500	$ (350)	$ (2,421)
Canada	1,229	7,330	9,181
Income taxes paid, net	40,488	9,905	9,365
Southwest Gas Corporation
Income Tax [Line Items]
Federal	585	0	0
State:	421	0	0
Income taxes paid, net	1,006	0	0
California
Income Tax [Line Items]
State:	8,502	0	0
Illinois
Income Tax [Line Items]
State:	2,060	0	0
Indiana
Income Tax [Line Items]
State:	0	509	0
Maryland
Income Tax [Line Items]
State:	0	1,104	0
Massachusetts
Income Tax [Line Items]
State:	0	512	0
Pennsylvania
Income Tax [Line Items]
State:	0	0	837
Texas
Income Tax [Line Items]
State:	0	0	723
Other states
Income Tax [Line Items]
State:	$ 4,197	$ 800	$ 1,045

Revision of Previously Issued Financial Statements

12 Months Ended

Dec. 31, 2025

Accounting Changes and Error Corrections [Abstract]

Revision of Previously Issued Financial Statements

Note 3 - Revision of Previously Issued Financial Statements

In connection with the preparation of the Company’s 2025 Form 10-K for Southwest Gas, management identified errors in the calculation of the estimated deferred income tax liabilities associated with state income taxes. The issues result from not timely updating estimated apportionment rates to reflect certain events. For Southwest Gas, the errors date back to the formation of Southwest Gas Holdings in 2017, when Southwest Gas and Centuri became wholly-owned subsidiaries of Southwest Gas Holdings. These errors were determined to be not material to any previously issued Southwest Gas financial statements. However, Southwest Gas revised the historical financial statements due to the magnitude of the cumulative effect of the prior year errors. Southwest Gas also revised the historical financial statements to correct other previously identified immaterial errors.

The effects of the correction of the errors on the Consolidated Financial Statements are as follows:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEET
(In thousands)

	December 31, 2024
	As Reported(1)		Adjustments		As Revised
ASSETS


Accounts receivable, net of allowance	$	202,947	$	(2,100)	$	200,847



Total current assets	859,055		(2,100)		856,955
Total assets	$	9,533,825	$	(2,100)	$	9,531,725
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,096,149	$	(36,376)	$	1,059,773
Total equity	3,271,862		(36,376)		3,235,486
Total capitalization	6,776,339		(36,376)		6,739,963
Accounts payable	190,612		1,997		192,609
Deferred purchased gas costs	255,398		(1,997)		253,401


Total current liabilities	769,026		—		769,026
Deferred income taxes and investment tax credits, net	819,973		34,276		854,249

Total deferred income taxes and other credits	1,988,460		34,276		2,022,736
Total capitalization and liabilities	$	9,533,825	$	(2,100)	$	9,531,725
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,475,216	$	7,774	$	2,482,990
Net cost of gas sold	1,150,005		7,359		1,157,364
Total operating expenses	2,062,885		7,359		2,070,244
Operating income	412,331		415		412,746
Income before income taxes	304,350		415		304,765
Income tax expense (benefit)	43,174		(505)		42,669
Net income	$	261,176	$	920	$	262,096






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,499,564	$	(5,344)	$	2,494,220
Net cost of gas sold	1,246,901		4,466		1,251,367
Operations and maintenance	511,646		(1,259)		510,387
Total operating expenses	2,141,270		3,207		2,144,477
Operating income (loss)	358,294		(8,551)		349,743
Income (loss) before income taxes	279,125		(8,551)		270,574
Income tax expense	36,899		5,263		42,162
Net income (loss)	$	242,226	$	(13,814)	$	228,412


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Net income	$	261,176	$	920	$	262,096
Comprehensive income	$	263,323	$	920	$	264,243






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Comprehensive income (loss)	$	239,939	$	(13,814)	$	226,125


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)

	Year Ended December 31, 2024
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	261,176	$	920	$	262,096
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	69,459		(505)		68,954
Changes in current assets and liabilities:
Accounts receivable, net of allowances	66,248		2,100		68,348
Deferred purchased gas costs	706,896		8,062		714,958
Accounts payable	(19,032)		(703)		(19,735)
Other current assets and liabilities	(57,917)		(9,874)		(67,791)
Net cash provided by operating activities	$	1,252,982	$	—	$	1,252,982
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.






	Year Ended December 31, 2023
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	66,611		5,263		71,874
Changes in current assets and liabilities:
Deferred purchased gas costs	192,182		(3,956)		188,226
Accounts payable	(260,403)		7,164		(253,239)
Other current assets and liabilities	14,516		5,343		19,859


Net cash provided by operating activities	$	391,545	$	—	$	391,545
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)

	As Reported		Adjustments		As Revised
Retained earnings, December 31, 2022	$	935,355	$	(23,482)	$	911,873
Total equity, December 31, 2022	2,569,175		(23,482)		2,545,693
Net income (loss) for the year ended December 31, 2023	242,226		(13,814)		228,412
Retained earnings, December 31, 2023	1,018,474		(37,296)		981,178
Total equity, December 31, 2023	3,183,615		(37,296)		3,146,319
Net income for the year ended December 31, 2024	261,176		920		262,096
Retained earnings, December 31, 2024	1,096,149		(36,376)		1,059,773
Total equity, December 31, 2024	$	3,271,862	$	(36,376)	$	3,235,486

Note 14 - Previously Issued Condensed Consolidated Financial Statements (Unaudited)

Southwest Gas Holdings, Inc.– Restatement of Previously Issued Condensed Consolidated Financial Statements

In connection with the preparation of this Form 10-K for the year ended December 31, 2025, management identified errors in the calculation of estimated deferred income tax liabilities associated with state income taxes. The errors arose following the Company’s sale of shares of Centuri’s common stock in the second and third quarters of 2025, which resulted in the tax deconsolidation of Centuri. The errors occurred because the Company did not update estimated future state apportionment rates following the Company’s sale of 13,207,142 shares of Centuri common stock on May 22, 2025, which resulted in income tax deconsolidation for Arizona, and subsequently following the Company's sale of 18,823,500 shares of Centuri common stock on August 11, 2025, which resulted in income tax deconsolidation for the remaining states, primarily California. As a result, income tax expense and net deferred income tax liabilities were understated by approximately $27.3 million as of and for the three and six months ended June 30, 2025, $7.8 million for the three months ended September 30, 2025 and $35.1 million as of and for the nine months ended September 30, 2025. Additionally, we corrected the September 30, 2025, Consolidated Balance Sheet for an error of $75.0 million related to the classification of current maturities of long-term debt which were included in long-term debt rather than short-term.

The Company intends to correct these financial statements through restatements when these periods are presented in a future periodic filing. The impact of the restatements are presented in the tables below for the three and six months ended June 30, 2025 and the three and nine months ended September 30, 2025. There is no impact to annual results as the errors originated and are being corrected within the same annual period.

The following tables summarize the impact of the correction of the errors to our restated unaudited Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Income, Consolidated Statements of Comprehensive Income, Consolidated Statements of Cash Flows and Consolidated Statements of Equity for each interim period for the three and six months ended June 30, 2025 and the three and nine months ended September 30, 2025. The amounts labeled “As Reported” were derived from our Quarterly Reports on Form 10-Q filed on August 6, 2025, and November 5, 2025, respectively.

The effects of the Company’s prior-period errors on our Condensed Consolidated Financial Statements are as follows:


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	June 30, 2025
	As Reported		Adjustments		As Restated(1)






















CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	769,723	$	(27,271)	$	742,452
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,674,657		(27,271)		3,647,386

Total equity	4,115,805		(27,271)		4,088,534


Total capitalization	8,520,371		(27,271)		8,493,100













Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	927,486		27,271		954,757



Total deferred income taxes and other credits	2,279,069		27,271		2,306,340
Total capitalization and liabilities	$	12,213,945	$	—	$	12,213,945

(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	September 30, 2025
	As Reported		Adjustments		As Restated
























CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	999,399	$	(35,113)	$	964,286
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,928,679		(35,113)		3,893,566

Total equity	3,928,679		(35,113)		3,893,566

Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	7,435,799		(110,113)		7,325,686
Current liabilities:
Current maturities of long-term debt	—		75,000		75,000










Total current liabilities	804,703		75,000		879,703
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	905,604		35,113		940,717



Total deferred income taxes and other credits	2,088,077		35,113		2,123,190
Total capitalization and liabilities	$	10,328,579	$	—	$	10,328,579


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
(In thousands, except per share amounts)
(Unaudited)


	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated(1)		As Reported		Adjustments		As Restated(1)

















Income tax expense (benefit)	$	52,594	$	27,271	$	79,865	$	80,263	$	27,271	$	107,534


Net income (loss)	(10,329)		(27,271)		(37,600)		98,858		(27,271)		71,587

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	(12,883)	$	(27,271)	$	(40,154)	$	100,987	$	(27,271)	$	73,716

Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.:


Basic	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02




Diluted	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02

Weighted average shares:
Basic	72,088				72,088		72,050				72,050
Diluted	72,088				72,088		72,195				72,195
(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated















Income tax expense (benefit)	$	(803)	$	7,842	$	7,039	$	36,059	$	35,113	$	71,172
Income (loss) from continuing operations	4,175		(7,842)		(3,667)		165,003		(35,113)		129,890

Net income (loss)	267,959		(7,842)		260,117		366,817		(35,113)		331,704

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	270,476	$	(7,842)	$	262,634	$	371,463	$	(35,113)	$	336,350

Basic earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.29	$	(0.49)	$	1.80

Net earnings (loss) per share - basic	$	3.75	$	(0.11)	$	3.64	$	5.15	$	(0.49)	$	4.66

Diluted earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.28	$	(0.49)	$	1.79

Net earnings (loss) per share - diluted	$	3.74	$	(0.11)	$	3.63	$	5.14	$	(0.49)	$	4.65

Weighted average shares:
Basic	72,209				72,209		72,104				72,104
Diluted	72,405				72,405		72,265				72,265


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	(10,329)	$	(27,271)	$	(37,600)	$	98,858	$	(27,271)	$	71,587









Comprehensive income (loss)	(3,351)		(27,271)		(30,622)		106,208		(27,271)		78,937

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	(6,970)	$	(27,271)	$	(34,241)	$	107,252	$	(27,271)	$	79,981






	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	267,959	$	(7,842)	$	260,117	$	366,817	$	(35,113)	$	331,704









Comprehensive income (loss)	266,566		(7,842)		258,724		372,774		(35,113)		337,661

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	269,879	$	(7,842)	$	262,037	$	377,131	$	(35,113)	$	342,018


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	98,858	$	(27,271)	$	71,587


Adjustments to reconcile net income (loss) to net cash provided by operating activities:

Deferred income taxes	94,033		27,271		121,304
Net cash provided by operating activities	$	417,611	$	—	$	417,611


	Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	366,817	$	(35,113)	$	331,704

Income (loss) from continuing operations, net of income tax	165,003		(35,113)		129,890
Adjustments to reconcile net income to net cash provided by operating activities:

Deferred income taxes	48,141		35,113		83,254
Net cash provided by operating activities of continuing operations	509,136		—		509,136

Net cash provided by operating activities	$	474,508	$	—	$	474,508


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Restated


Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended June 30, 2025	$	(12,883)	$	(27,271)	$	(40,154)
Retained earnings, June 30, 2025	769,723		(27,271)		742,452
Total equity attributable to Southwest Gas Holdings, Inc., June 30, 2025	3,674,657		(27,271)		3,647,386
Total equity, June 30, 2025	4,115,805		(27,271)		4,088,534
Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended September 30, 2025	270,476		(7,842)		262,634
Retained earnings, September 30, 2025	999,399		(35,113)		964,286
Total equity attributable to Southwest Gas Holdings, Inc., September 30, 2025	3,928,679		(35,113)		3,893,566
Total equity, September 30, 2025	$	3,928,679	$	(35,113)	$	3,893,566

Southwest Gas Corporation – Revision of Previously Issued Financial Statements

As discussed in Note 3 - Revision of Previously Issued Financial Statements, in connection with the preparation of the Company’s 2025 Form 10-K, management identified errors in the calculation of the estimated deferred income tax liabilities associated with state income taxes. The issues result from not timely updating estimated apportionment rates to reflect certain events. For Southwest Gas, the errors date back to the formation of Southwest Gas Holdings in 2017, when Southwest Gas and Centuri became wholly-owned subsidiaries of Southwest Gas Holdings. These errors were determined to be not material to any previously issued Southwest Gas financial statements. As a result of the cumulative magnitude of the error, Southwest Gas revised the historical financial statements. Southwest Gas also revised the historical financial statements to correct other previously identified immaterial errors.

The Company intends to correct these financial statements through revisions when these periods are presented in a future periodic filing. The impacts of the revisions are presented in the tables below:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	March 31, 2025
	As Reported		Adjustments		As Revised



CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,238,775	$	(36,723)	$	1,202,052
Total equity	3,416,872		(36,723)		3,380,149
Total capitalization	6,922,224		(36,723)		6,885,501


Deferred income taxes and investment tax credits, net	857,986		36,723		894,709
Total deferred income taxes and other credits	2,025,235		36,723		2,061,958
Total capitalization and liabilities	$	9,679,467	$	—	$	9,679,467






	June 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,227,760	$	(24,754)	$	1,203,006
Total equity	3,408,373		(24,754)		3,383,619
Total capitalization	6,914,610		(24,754)		6,889,856


Deferred income taxes and investment tax credits, net	871,647		24,754		896,401
Total deferred income taxes and other credits	2,047,726		24,754		2,072,480
Total capitalization and liabilities	$	9,688,433	$	—	$	9,688,433






	September 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,233,196	$	(23,931)	$	1,209,265
Total equity	3,416,463		(23,931)		3,392,532
Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	6,923,583		(98,931)		6,824,652
Current maturities of long-term debt	—		75,000		75,000
Total current liabilities	751,278		75,000		826,278
Deferred income taxes and investment tax credits, net	872,344		23,931		896,275
Total deferred income taxes and other credits	2,050,616		23,931		2,074,547
Total capitalization and liabilities	$	9,725,477	$	—	$	9,725,477


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	746,416	$	2,100	$	748,516
Operating income	214,979		2,100		217,079
Income before income taxes	179,650		2,100		181,750
Income tax expense	36,708		2,447		39,155
Net income (loss)	$	142,942	$	(347)	$	142,595







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	396,318	$	—	$	396,318	$	1,142,734	$	2,100	$	1,144,834
Operating income	65,342		—		65,342		280,321		2,100		282,421
Income before income taxes	38,411		—		38,411		218,061		2,100		220,161
Income tax expense (benefit)	4,734		(11,969)		(7,235)		41,442		(9,522)		31,920
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	316,911	$	—	$	316,911	$	1,459,645	$	2,100	$	1,461,745
Operating income	37,977		—		37,977		318,298		2,100		320,398
Income before income taxes	5,098		—		5,098		223,159		2,100		225,259
Income tax expense (benefit)	(422)		(823)		(1,245)		41,020		(10,345)		30,675
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Net income (loss)	$	142,942	$	(347)	$	142,595
Comprehensive income (loss)	$	143,210	$	(347)	$	142,863







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241
Comprehensive income	$	33,944	$	11,969	$	45,913	$	177,154	$	11,622	$	188,776







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584
Comprehensive income	$	5,789	$	823	$	6,612	$	182,943	$	12,445	$	195,388


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Three Month Ended March 31, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	142,942	$	(347)	$	142,595
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	37,928		2,447		40,375
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(11,117)		(2,100)		(13,217)
Deferred purchased gas costs	53,865		1,997		55,862
Accounts payable	(44,691)		(1,997)		(46,688)
Net cash provided by operating activities	$	285,832	$	—	$	285,832







	Six Month Ended June 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	176,619	$	11,622	$	188,241
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	51,504		(9,522)		41,982
Changes in current assets and liabilities:
Accounts receivable, net of allowance	68,311		(2,100)		66,211
Deferred purchased gas costs	120,709		1,997		122,706
Accounts payable	(69,232)		(1,997)		(71,229)
Net cash provided by operating activities	$	459,287	$	—	$	459,287







	Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	182,139	$	12,445	$	194,584
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	52,890		(10,345)		42,545
Changes in current assets and liabilities:
Accounts receivable, net of allowance	92,372		(2,100)		90,272
Deferred purchased gas costs	114,768		1,997		116,765
Accounts payable	(66,237)		(1,997)		(68,234)
Net cash provided by operating activities	$	526,359	$	—	$	526,359


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Revised


Net income (loss), for the three months ended March 31, 2025	$	142,942	$	(347)	$	142,595
Retained earnings, March 31, 2025	1,238,775		(36,723)		1,202,052
Total Equity, March 31, 2025	3,416,872		(36,723)		3,380,149
Net income for the three months ended June 30, 2025	33,677		11,969		45,646
Retained earnings, June 30, 2025	1,227,760		(24,754)		1,203,006
Total Equity, June 30, 2025	3,408,373		(24,754)		3,383,619
Net income (loss) for the three months ended September 30, 2025	5,520		823		6,343
Retained earnings, September 30, 2025	1,233,196		(23,931)		1,209,265
Total Equity, September 30, 2025	$	3,416,463	$	(23,931)	$	3,392,532

Previously Issued Condensed Consolidated Financial Statements (Unaudited)

12 Months Ended

Dec. 31, 2025

Accounting Changes and Error Corrections [Abstract]

Previously Issued Condensed Consolidated Financial Statements (Unaudited)

Note 3 - Revision of Previously Issued Financial Statements

The effects of the correction of the errors on the Consolidated Financial Statements are as follows:


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEET
(In thousands)

	December 31, 2024
	As Reported(1)		Adjustments		As Revised
ASSETS


Accounts receivable, net of allowance	$	202,947	$	(2,100)	$	200,847



Total current assets	859,055		(2,100)		856,955
Total assets	$	9,533,825	$	(2,100)	$	9,531,725
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,096,149	$	(36,376)	$	1,059,773
Total equity	3,271,862		(36,376)		3,235,486
Total capitalization	6,776,339		(36,376)		6,739,963
Accounts payable	190,612		1,997		192,609
Deferred purchased gas costs	255,398		(1,997)		253,401


Total current liabilities	769,026		—		769,026
Deferred income taxes and investment tax credits, net	819,973		34,276		854,249

Total deferred income taxes and other credits	1,988,460		34,276		2,022,736
Total capitalization and liabilities	$	9,533,825	$	(2,100)	$	9,531,725
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,475,216	$	7,774	$	2,482,990
Net cost of gas sold	1,150,005		7,359		1,157,364
Total operating expenses	2,062,885		7,359		2,070,244
Operating income	412,331		415		412,746
Income before income taxes	304,350		415		304,765
Income tax expense (benefit)	43,174		(505)		42,669
Net income	$	261,176	$	920	$	262,096






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	2,499,564	$	(5,344)	$	2,494,220
Net cost of gas sold	1,246,901		4,466		1,251,367
Operations and maintenance	511,646		(1,259)		510,387
Total operating expenses	2,141,270		3,207		2,144,477
Operating income (loss)	358,294		(8,551)		349,743
Income (loss) before income taxes	279,125		(8,551)		270,574
Income tax expense	36,899		5,263		42,162
Net income (loss)	$	242,226	$	(13,814)	$	228,412


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)

	Year Ended December 31, 2024
	As Reported		Adjustments		As Revised
Net income	$	261,176	$	920	$	262,096
Comprehensive income	$	263,323	$	920	$	264,243






	Year Ended December 31, 2023
	As Reported		Adjustments		As Revised
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Comprehensive income (loss)	$	239,939	$	(13,814)	$	226,125


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)

	Year Ended December 31, 2024
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	261,176	$	920	$	262,096
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	69,459		(505)		68,954
Changes in current assets and liabilities:
Accounts receivable, net of allowances	66,248		2,100		68,348
Deferred purchased gas costs	706,896		8,062		714,958
Accounts payable	(19,032)		(703)		(19,735)
Other current assets and liabilities	(57,917)		(9,874)		(67,791)
Net cash provided by operating activities	$	1,252,982	$	—	$	1,252,982
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.






	Year Ended December 31, 2023
	As Reported(1)		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	242,226	$	(13,814)	$	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	66,611		5,263		71,874
Changes in current assets and liabilities:
Deferred purchased gas costs	192,182		(3,956)		188,226
Accounts payable	(260,403)		7,164		(253,239)
Other current assets and liabilities	14,516		5,343		19,859


Net cash provided by operating activities	$	391,545	$	—	$	391,545
(1) Previously reported amounts also reflect the reclassification discussed in Note 2 - Summary of Significant Accounting Policies.


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)

	As Reported		Adjustments		As Revised
Retained earnings, December 31, 2022	$	935,355	$	(23,482)	$	911,873
Total equity, December 31, 2022	2,569,175		(23,482)		2,545,693
Net income (loss) for the year ended December 31, 2023	242,226		(13,814)		228,412
Retained earnings, December 31, 2023	1,018,474		(37,296)		981,178
Total equity, December 31, 2023	3,183,615		(37,296)		3,146,319
Net income for the year ended December 31, 2024	261,176		920		262,096
Retained earnings, December 31, 2024	1,096,149		(36,376)		1,059,773
Total equity, December 31, 2024	$	3,271,862	$	(36,376)	$	3,235,486

Note 14 - Previously Issued Condensed Consolidated Financial Statements (Unaudited)

Southwest Gas Holdings, Inc.– Restatement of Previously Issued Condensed Consolidated Financial Statements

The effects of the Company’s prior-period errors on our Condensed Consolidated Financial Statements are as follows:


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	June 30, 2025
	As Reported		Adjustments		As Restated(1)






















CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	769,723	$	(27,271)	$	742,452
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,674,657		(27,271)		3,647,386

Total equity	4,115,805		(27,271)		4,088,534


Total capitalization	8,520,371		(27,271)		8,493,100













Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	927,486		27,271		954,757



Total deferred income taxes and other credits	2,279,069		27,271		2,306,340
Total capitalization and liabilities	$	12,213,945	$	—	$	12,213,945

(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	September 30, 2025
	As Reported		Adjustments		As Restated
























CAPITALIZATION AND LIABILITIES
Capitalization:



Retained earnings	$	999,399	$	(35,113)	$	964,286
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,928,679		(35,113)		3,893,566

Total equity	3,928,679		(35,113)		3,893,566

Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	7,435,799		(110,113)		7,325,686
Current liabilities:
Current maturities of long-term debt	—		75,000		75,000










Total current liabilities	804,703		75,000		879,703
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	905,604		35,113		940,717



Total deferred income taxes and other credits	2,088,077		35,113		2,123,190
Total capitalization and liabilities	$	10,328,579	$	—	$	10,328,579


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
(In thousands, except per share amounts)
(Unaudited)


	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated(1)		As Reported		Adjustments		As Restated(1)

















Income tax expense (benefit)	$	52,594	$	27,271	$	79,865	$	80,263	$	27,271	$	107,534


Net income (loss)	(10,329)		(27,271)		(37,600)		98,858		(27,271)		71,587

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	(12,883)	$	(27,271)	$	(40,154)	$	100,987	$	(27,271)	$	73,716

Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.:


Basic	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02




Diluted	$	(0.18)	$	(0.38)	$	(0.56)	$	1.40	$	(0.38)	$	1.02

Weighted average shares:
Basic	72,088				72,088		72,050				72,050
Diluted	72,088				72,088		72,195				72,195
(1) Will be recast for discontinued operations for the sale of Centuri when this is presented in a future filing.


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated















Income tax expense (benefit)	$	(803)	$	7,842	$	7,039	$	36,059	$	35,113	$	71,172
Income (loss) from continuing operations	4,175		(7,842)		(3,667)		165,003		(35,113)		129,890

Net income (loss)	267,959		(7,842)		260,117		366,817		(35,113)		331,704

Net income (loss) attributable to Southwest Gas Holdings, Inc.	$	270,476	$	(7,842)	$	262,634	$	371,463	$	(35,113)	$	336,350

Basic earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.29	$	(0.49)	$	1.80

Net earnings (loss) per share - basic	$	3.75	$	(0.11)	$	3.64	$	5.15	$	(0.49)	$	4.66

Diluted earnings (loss) per share:
Continuing operations	$	0.06	$	(0.11)	$	(0.05)	$	2.28	$	(0.49)	$	1.79

Net earnings (loss) per share - diluted	$	3.74	$	(0.11)	$	3.63	$	5.14	$	(0.49)	$	4.65

Weighted average shares:
Basic	72,209				72,209		72,104				72,104
Diluted	72,405				72,405		72,265				72,265


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	(10,329)	$	(27,271)	$	(37,600)	$	98,858	$	(27,271)	$	71,587









Comprehensive income (loss)	(3,351)		(27,271)		(30,622)		106,208		(27,271)		78,937

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	(6,970)	$	(27,271)	$	(34,241)	$	107,252	$	(27,271)	$	79,981






	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Restated		As Reported		Adjustments		As Restated
Net income (loss)	$	267,959	$	(7,842)	$	260,117	$	366,817	$	(35,113)	$	331,704









Comprehensive income (loss)	266,566		(7,842)		258,724		372,774		(35,113)		337,661

Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$	269,879	$	(7,842)	$	262,037	$	377,131	$	(35,113)	$	342,018


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Six Months Ended June 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	98,858	$	(27,271)	$	71,587


Adjustments to reconcile net income (loss) to net cash provided by operating activities:

Deferred income taxes	94,033		27,271		121,304
Net cash provided by operating activities	$	417,611	$	—	$	417,611


	Nine Months Ended September 30, 2025
	As Reported		Adjustments		As Restated
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	366,817	$	(35,113)	$	331,704

Income (loss) from continuing operations, net of income tax	165,003		(35,113)		129,890
Adjustments to reconcile net income to net cash provided by operating activities:

Deferred income taxes	48,141		35,113		83,254
Net cash provided by operating activities of continuing operations	509,136		—		509,136

Net cash provided by operating activities	$	474,508	$	—	$	474,508


SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Restated


Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended June 30, 2025	$	(12,883)	$	(27,271)	$	(40,154)
Retained earnings, June 30, 2025	769,723		(27,271)		742,452
Total equity attributable to Southwest Gas Holdings, Inc., June 30, 2025	3,674,657		(27,271)		3,647,386
Total equity, June 30, 2025	4,115,805		(27,271)		4,088,534
Net income (loss) attributable to Southwest Gas Holdings, Inc., for the three months ended September 30, 2025	270,476		(7,842)		262,634
Retained earnings, September 30, 2025	999,399		(35,113)		964,286
Total equity attributable to Southwest Gas Holdings, Inc., September 30, 2025	3,928,679		(35,113)		3,893,566
Total equity, September 30, 2025	$	3,928,679	$	(35,113)	$	3,893,566

Southwest Gas Corporation – Revision of Previously Issued Financial Statements


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS
(In thousands)
(Unaudited)

	March 31, 2025
	As Reported		Adjustments		As Revised



CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,238,775	$	(36,723)	$	1,202,052
Total equity	3,416,872		(36,723)		3,380,149
Total capitalization	6,922,224		(36,723)		6,885,501


Deferred income taxes and investment tax credits, net	857,986		36,723		894,709
Total deferred income taxes and other credits	2,025,235		36,723		2,061,958
Total capitalization and liabilities	$	9,679,467	$	—	$	9,679,467






	June 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,227,760	$	(24,754)	$	1,203,006
Total equity	3,408,373		(24,754)		3,383,619
Total capitalization	6,914,610		(24,754)		6,889,856


Deferred income taxes and investment tax credits, net	871,647		24,754		896,401
Total deferred income taxes and other credits	2,047,726		24,754		2,072,480
Total capitalization and liabilities	$	9,688,433	$	—	$	9,688,433






	September 30, 2025
	As Reported		Adjustments		As Revised
CAPITALIZATION AND LIABILITIES
Retained earnings	$	1,233,196	$	(23,931)	$	1,209,265
Total equity	3,416,463		(23,931)		3,392,532
Long-term debt, less current maturities	3,507,120		(75,000)		3,432,120
Total capitalization	6,923,583		(98,931)		6,824,652
Current maturities of long-term debt	—		75,000		75,000
Total current liabilities	751,278		75,000		826,278
Deferred income taxes and investment tax credits, net	872,344		23,931		896,275
Total deferred income taxes and other credits	2,050,616		23,931		2,074,547
Total capitalization and liabilities	$	9,725,477	$	—	$	9,725,477


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Regulated operations revenues	$	746,416	$	2,100	$	748,516
Operating income	214,979		2,100		217,079
Income before income taxes	179,650		2,100		181,750
Income tax expense	36,708		2,447		39,155
Net income (loss)	$	142,942	$	(347)	$	142,595







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	396,318	$	—	$	396,318	$	1,142,734	$	2,100	$	1,144,834
Operating income	65,342		—		65,342		280,321		2,100		282,421
Income before income taxes	38,411		—		38,411		218,061		2,100		220,161
Income tax expense (benefit)	4,734		(11,969)		(7,235)		41,442		(9,522)		31,920
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Regulated operations revenues	$	316,911	$	—	$	316,911	$	1,459,645	$	2,100	$	1,461,745
Operating income	37,977		—		37,977		318,298		2,100		320,398
Income before income taxes	5,098		—		5,098		223,159		2,100		225,259
Income tax expense (benefit)	(422)		(823)		(1,245)		41,020		(10,345)		30,675
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
(In thousands)
(Unaudited)

	Three Months Ended March 31, 2025
	As Reported		Adjustments		As Revised
Net income (loss)	$	142,942	$	(347)	$	142,595
Comprehensive income (loss)	$	143,210	$	(347)	$	142,863







	Three Months Ended June 30, 2025						Six Months Ended June 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	33,677	$	11,969	$	45,646	$	176,619	$	11,622	$	188,241
Comprehensive income	$	33,944	$	11,969	$	45,913	$	177,154	$	11,622	$	188,776







	Three Month Ended September 30, 2025						Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income	$	5,520	$	823	$	6,343	$	182,139	$	12,445	$	194,584
Comprehensive income	$	5,789	$	823	$	6,612	$	182,943	$	12,445	$	195,388


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

	Three Month Ended March 31, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$	142,942	$	(347)	$	142,595
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	37,928		2,447		40,375
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(11,117)		(2,100)		(13,217)
Deferred purchased gas costs	53,865		1,997		55,862
Accounts payable	(44,691)		(1,997)		(46,688)
Net cash provided by operating activities	$	285,832	$	—	$	285,832







	Six Month Ended June 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	176,619	$	11,622	$	188,241
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	51,504		(9,522)		41,982
Changes in current assets and liabilities:
Accounts receivable, net of allowance	68,311		(2,100)		66,211
Deferred purchased gas costs	120,709		1,997		122,706
Accounts payable	(69,232)		(1,997)		(71,229)
Net cash provided by operating activities	$	459,287	$	—	$	459,287







	Nine Month Ended September 30, 2025
	As Reported		Adjustments		As Revised
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	182,139	$	12,445	$	194,584
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	52,890		(10,345)		42,545
Changes in current assets and liabilities:
Accounts receivable, net of allowance	92,372		(2,100)		90,272
Deferred purchased gas costs	114,768		1,997		116,765
Accounts payable	(66,237)		(1,997)		(68,234)
Net cash provided by operating activities	$	526,359	$	—	$	526,359


SOUTHWEST GAS CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF EQUITY
(In thousands)
(Unaudited)

	As Reported		Adjustments		As Revised


Net income (loss), for the three months ended March 31, 2025	$	142,942	$	(347)	$	142,595
Retained earnings, March 31, 2025	1,238,775		(36,723)		1,202,052
Total Equity, March 31, 2025	3,416,872		(36,723)		3,380,149
Net income for the three months ended June 30, 2025	33,677		11,969		45,646
Retained earnings, June 30, 2025	1,227,760		(24,754)		1,203,006
Total Equity, June 30, 2025	3,408,373		(24,754)		3,383,619
Net income (loss) for the three months ended September 30, 2025	5,520		823		6,343
Retained earnings, September 30, 2025	1,233,196		(23,931)		1,209,265
Total Equity, September 30, 2025	$	3,416,463	$	(23,931)	$	3,392,532

Share-Based Compensation - Schedule of Share-Based Plan Compensation Expense, Including Cash Award (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 23,336	$ 14,899	$ 8,079
Total tax benefit	3,783	2,848	1,939
Continuing Operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	14,631	11,372	6,228
Total tax benefit	2,244	2,051	1,495
Discontinued Operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	8,705	3,527	1,851
Total tax benefit	$ 1,539	$ 797	$ 444

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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CONSOLIDATED BALANCE SHEETS - Southwest - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Regulated operations plant:
Gas plant	$ 11,517,031	$ 10,844,895
Less: accumulated depreciation	(3,063,363)	(2,914,457)
Construction work in progress	236,871	178,647
Net regulated operations plant	8,690,539	8,109,085
Other property and investments, net	178,826	165,448
Current assets:
Cash and cash equivalents	576,645	314,770
Accounts receivable, net of allowances	170,601	203,012
Accrued utility revenue	101,600	96,600
Income taxes receivable, net	9,611	0
Deferred purchased gas costs	5,214	13,807
Materials, supplies & gas inventories	93,823	93,755
Prepaid and other current assets	234,598	141,017
Total current assets	1,192,092	1,464,345
Noncurrent assets:
Goodwill	11,155	11,155
Deferred charges and other assets	356,865	395,747
Total noncurrent assets	368,020	2,334,028
Total assets	10,429,477	12,072,906
Capitalization:
Common stock	73,854	73,413
Additional paid-in capital	2,898,965	2,721,343
Accumulated other comprehensive loss, net	(34,546)	(49,218)
Retained earnings	1,022,846	758,649
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,961,119	3,504,187
Long-term debt, less current maturities	3,433,012	3,504,477
Total capitalization	7,394,131	7,193,559
Commitments and contingencies (Note 15)
Current liabilities:
Current maturities of long-term debt	75,000	0
Accounts payable	225,732	190,918
Customer deposits	67,249	63,876
Accrued general taxes	54,384	59,353
Accrued interest	35,319	35,668
Deferred purchased gas costs	310,085	255,398
Dividends declared	44,779	44,505
Other current liabilities	117,350	119,357
Total current liabilities	929,898	1,831,967
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	977,312	857,982
Accumulated removal costs	496,000	472,000
Other deferred credits and other long-term liabilities	632,136	700,672
Total deferred income taxes and other credits	2,105,448	3,047,380
Total capitalization and liabilities	10,429,477	12,072,906
Southwest Gas Corporation
Regulated operations plant:
Gas plant	11,517,031	10,844,895
Less: accumulated depreciation	(3,063,363)	(2,914,457)
Construction work in progress	236,871	178,647
Net regulated operations plant	8,690,539	8,109,085
Other property and investments, net	169,947	159,678
Current assets:
Cash and cash equivalents	56,408	311,073
Accounts receivable, net of allowances		200,847
Accrued utility revenue	101,600	96,600
Income taxes receivable, net	1,007	0
Deferred purchased gas costs	5,214	13,807
Materials, supplies & gas inventories	93,823	93,755
Prepaid and other current assets	234,003	140,873
Total current assets	768,129	856,955
Noncurrent assets:
Goodwill	11,155	11,155
Deferred charges and other assets	354,221	394,852
Total noncurrent assets	365,376	406,007
Total assets	9,993,991	9,531,725
Capitalization:
Common stock	49,112	49,112
Additional paid-in capital	2,195,489	2,165,002
Accumulated other comprehensive loss, net	(34,546)	(38,401)
Retained earnings	1,314,911	1,059,773
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,524,966	3,235,486
Long-term debt, less current maturities	3,433,012	3,504,477
Total capitalization	6,957,978	6,739,963
Commitments and contingencies (Note 15)
Current liabilities:
Current maturities of long-term debt	75,000	0
Accounts payable		192,609
Customer deposits	67,249	63,876
Accrued general taxes	54,384	59,353
Accrued interest	35,319	35,460
Deferred purchased gas costs	310,085	253,401
Dividends declared	0	44,600
Other current liabilities	117,350	119,357
Total current liabilities	884,724	769,026
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	1,027,921	854,249
Accumulated removal costs	496,000	472,000
Other deferred credits and other long-term liabilities	627,368	696,487
Total deferred income taxes and other credits	2,151,289	2,022,736
Total capitalization and liabilities	9,993,991	9,531,725
Southwest Gas Corporation \| Nonrelated Party
Current assets:
Accounts receivable, net of allowances	170,524	200,847
Current liabilities:
Accounts payable	225,337	192,609
Southwest Gas Corporation \| Related Party
Current assets:
Accounts receivable, net of allowances	105,550	0
Current liabilities:
Accounts payable	$ 0	$ 370

Regulatory Assets and Liabilities - Schedule of Components of Other Regulatory Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Regulatory Assets [Line Items]
Regulatory assets	$ 519,737	$ 494,088
State mandated public purpose programs (including low income and conservation programs)
Regulatory Assets [Line Items]
Regulatory assets	21,308	24,404
Infrastructure replacement programs and similar
Regulatory Assets [Line Items]
Regulatory assets	32,516	24,262
Environmental compliance programs
Regulatory Assets [Line Items]
Regulatory assets	7,087	3,730
Environmental compliance programs \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets	5,500	2,600
Environmental compliance programs \| Deferred charges and other assets
Regulatory Assets [Line Items]
Regulatory assets	1,600	1,100
Pension tracking mechanism
Regulatory Assets [Line Items]
Regulatory assets	16,727	16,151
Other
Regulatory Assets [Line Items]
Regulatory assets	15,182	21,536
Other \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets	7,600	11,700
Other \| Deferred charges and other assets
Regulatory Assets [Line Items]
Regulatory assets	7,600	9,900
Other regulatory assets
Regulatory Assets [Line Items]
Regulatory assets	$ 92,820	$ 90,083

Pension and Other Postretirement Benefits - Schedule of Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
QRP
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,091,081	$ 1,084,462
SERP
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 42,382	$ 40,753

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Pension and Other Postretirement Benefits - Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$ (54,640)	$ (4,842)	$ 3,188
Amortization of prior service cost	(175)	(175)	(175)
Amortization of net actuarial loss	(3,775)	(7,641)	(1,333)
Regulatory adjustment	53,517	9,833	1,330
Recognized in other comprehensive (income) loss	(5,073)	(2,825)	3,010
Net periodic benefit costs recognized in net income	8,318	13,259	6,972
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	3,245	10,434	9,982
QRP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(55,680)	(659)	455
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	(3,007)	(6,308)	(335)
Regulatory adjustment	52,232	6,200	(107)
Recognized in other comprehensive (income) loss	(6,455)	(767)	13
Net periodic benefit costs recognized in net income	2,661	7,135	1,279
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	(3,794)	6,368	1,292
SERP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	2,463	(725)	3,995
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	(1,081)	(1,333)	(998)
Regulatory adjustment	0	0	0
Recognized in other comprehensive (income) loss	1,382	(2,058)	2,997
Net periodic benefit costs recognized in net income	3,696	3,743	3,371
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	5,078	1,685	6,368
PBOP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(1,423)	(3,458)	(1,262)
Amortization of prior service cost	(175)	(175)	(175)
Amortization of net actuarial loss	313	0	0
Regulatory adjustment	1,285	3,633	1,437
Recognized in other comprehensive (income) loss	0	0	0
Net periodic benefit costs recognized in net income	1,961	2,381	2,322
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$ 1,961	$ 2,381	$ 2,322

Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Other property	$ 8,879	$ 5,770
Other property and investments	178,826	165,448
Southwest Gas Corporation
Property, Plant and Equipment [Line Items]
Net cash surrender value of COLI policies	165,551	155,199
Other property	4,396	4,479
Other property and investments	$ 169,947	$ 159,678

Regulatory Assets and Liabilities - Narrative (Details)	12 Months Ended
Regulatory Assets and Liabilities - Narrative (Details)	Dec. 31, 2025
Regulated Operations [Abstract]
Regulatory assets (liability), no return on investment, recovery period	12 months
Regulatory assets (liability), return on investment, recovery period	12 months

Summary of Significant Accounting Policies - Schedule of Other Income (Deductions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Other income (deductions)
Interest income			$ 50,757
Equity AFUDC	$ 5,809	$ 6,597	1,951
Equity in earnings of unconsolidated investments	0	0	394
Miscellaneous income and (expense)	0	0	(49)
Corporate and administrative	7,666	(84)	151
Total other income (deductions)	60,068	54,192	71,239
Southwest Gas Corporation
Other income (deductions)
Change in COLI policies	10,300	8,400	10,100
Interest income	20,944	33,581	50,757
Equity AFUDC	5,809	6,597	1,869
Non-service components of net periodic benefit cost	17,475	16,523	20,387
Miscellaneous income and (expense)	(2,126)	(10,825)	(12,452)
Total other income (deductions)	52,402	54,276	70,661
MountainWest Pipelines Holding Company
Other income (deductions)
Equity AFUDC	$ 0	$ 0	$ 82

Summary of Significant Accounting Policies - Schedule of Earnings Per Share, Basic and Diluted (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Weighted average basic shares (in shares)	72,209	72,088	72,050	72,104	72,162	71,841	70,787
Effect of dilutive securities:
Restricted stock units (in shares)					175	191	203
Weighted average diluted shares (in shares)	72,405	72,088	72,195	72,265	72,337	72,032	70,990
Number of performance share units granted (in shares)					146	158	173
Antidilutive securities (in shares)						191

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2025
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Las Vegas, Nevada
Auditor Firm ID	238
Southwest Gas Corporation
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Las Vegas, Nevada
Auditor Firm ID	238

Revision of Previously Issued Financial Statements - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 260,117	$ (37,600)		$ 71,587	$ 331,704	$ 435,180	$ 204,836	$ 155,517
Comprehensive income (loss)	258,724	(30,622)		78,937	337,661	444,188	196,860	155,972
Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	6,343	45,646	$ 142,595	188,241	194,584	300,308	262,096	228,412
Comprehensive income (loss)	6,612	45,913	142,863	188,776	195,388	$ 304,163	264,243	226,125
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	267,959	(10,329)		98,858	366,817
Comprehensive income (loss)	266,566	(3,351)		106,208	372,774
As Reported \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	5,520	33,677	142,942	176,619	182,139		261,176	242,226
Comprehensive income (loss)	5,789	33,944	143,210	177,154	182,943		263,323	239,939
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Comprehensive income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Adjustments \| Southwest Gas Corporation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	823	11,969	(347)	11,622	12,445		920	(13,814)
Comprehensive income (loss)	$ 823	$ 11,969	$ (347)	$ 11,622	$ 12,445		$ 920	$ (13,814)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

Revenue - Schedule of Revenue Disaggregated by Service Type and Contract Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total Regulated operations revenues	$ 1,940,380	$ 2,475,216	$ 2,534,696
Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,843,972	2,438,523	2,536,079
Alternative revenue program revenues	86,593	23,055	(52,365)
Other revenues	9,815	13,638	15,850
Total Regulated operations revenues	1,940,380	2,475,216	2,499,564
Residential \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,276,677	1,654,685	1,725,223
Small commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	333,408	493,709	513,366
Large commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	72,367	111,350	117,973
Industrial and other \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	44,941	62,997	75,219
Transportation \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 116,579	$ 115,782	$ 104,298

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Common stock, par (in USD per share)	$ 1	$ 1
Common stock, authorized (in shares)	120,000,000	120,000,000
Common stock, issued (in shares)	72,224,593	71,782,756
Common stock, outstanding (in shares)	72,224,593	71,782,756

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - Southwest (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net actuarial gain (loss), tax expense (benefit)	$ 13,114	$ 1,162	$ (765)
Amortization of prior service cost, tax expense	(42)	(42)	(42)
Amortization of net actuarial loss, tax expense	(906)	(1,834)	(319)
Regulatory adjustment, tax benefit	(12,844)	(2,360)	(319)
Southwest Gas Corporation
Net actuarial gain (loss), tax expense (benefit)	13,114	1,162	(765)
Amortization of prior service cost, tax expense	42	42	42
Amortization of net actuarial loss, tax expense	906	1,834	319
Regulatory adjustment, tax benefit	$ (12,844)	$ (2,360)	$ (319)

Previously Issued Condensed Consolidated Financial Statements (Unaudited) - Schedule of Effects of the Prior-Period Errors on the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Capitalization:
Retained earnings	$ 1,022,846	$ 964,286	$ 742,452		$ 758,649
Total equity	3,961,119	3,893,566	3,647,386		3,504,187
Total equity	3,961,119	3,893,566	4,088,534		3,681,422	$ 3,310,036	$ 3,058,759
Long-term debt, less current maturities	3,433,012	3,432,120			3,504,477
Total capitalization	7,394,131	7,325,686	8,493,100		7,193,559
Current liabilities:
Current maturities of long-term debt	75,000	75,000			0
Total current liabilities	929,898	879,703			1,831,967
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	977,312	940,717	954,757		857,982
Total deferred income taxes and other credits	2,105,448	2,123,190	2,306,340		3,047,380
Total capitalization and liabilities	10,429,477	10,328,579	12,213,945		12,072,906
Southwest Gas Corporation
Capitalization:
Retained earnings	1,314,911	1,209,265	1,203,006	$ 1,202,052	1,059,773
Total equity	3,524,966	3,392,532	3,383,619	3,380,149	3,235,486
Total equity	3,524,966	3,392,532	3,383,619	3,380,149	3,235,486	3,146,319	2,545,693
Long-term debt, less current maturities	3,433,012	3,432,120			3,504,477
Total capitalization	6,957,978	6,824,652	6,889,856	6,885,501	6,739,963
Current liabilities:
Current maturities of long-term debt	75,000	75,000			0
Total current liabilities	884,724	826,278			769,026
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	1,027,921	896,275	896,401	894,709	854,249
Total deferred income taxes and other credits	2,151,289	2,074,547	2,072,480	2,061,958	2,022,736
Total capitalization and liabilities	$ 9,993,991	9,725,477	9,688,433	9,679,467	9,531,725
As Reported
Capitalization:
Retained earnings		999,399	769,723
Total equity		3,928,679	3,674,657
Total equity		3,928,679	4,115,805
Long-term debt, less current maturities		3,507,120
Total capitalization		7,435,799	8,520,371
Current liabilities:
Current maturities of long-term debt		0
Total current liabilities		804,703			769,026
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net		905,604	927,486
Total deferred income taxes and other credits		2,088,077	2,279,069
Total capitalization and liabilities		10,328,579	12,213,945
As Reported \| Southwest Gas Corporation
Capitalization:
Retained earnings		1,233,196	1,227,760	1,238,775	1,096,149
Total equity		3,416,463	3,408,373	3,416,872	3,271,862
Total equity		3,416,463	3,408,373	3,416,872	3,271,862	3,183,615	2,569,175
Long-term debt, less current maturities		3,507,120
Total capitalization		6,923,583	6,914,610	6,922,224	6,776,339
Current liabilities:
Current maturities of long-term debt		0
Total current liabilities		751,278
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net		872,344	871,647	857,986	819,973
Total deferred income taxes and other credits		2,050,616	2,047,726	2,025,235	1,988,460
Total capitalization and liabilities		9,725,477	9,688,433	9,679,467	9,533,825
Adjustments
Capitalization:
Retained earnings		(35,113)	(27,271)
Total equity		(35,113)	(27,271)
Total equity		(35,113)	(27,271)
Long-term debt, less current maturities		(75,000)
Total capitalization		(110,113)	(27,271)
Current liabilities:
Current maturities of long-term debt		75,000
Total current liabilities		75,000			0
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net		35,113	27,271
Total deferred income taxes and other credits		35,113	27,271
Total capitalization and liabilities		0	0
Adjustments \| Southwest Gas Corporation
Capitalization:
Retained earnings		(23,931)	(24,754)	(36,723)	(36,376)
Total equity		(23,931)	(24,754)	(36,723)	(36,376)
Total equity		(23,931)	(24,754)	(36,723)	(36,376)	$ (37,296)	$ (23,482)
Long-term debt, less current maturities		(75,000)
Total capitalization		(98,931)	(24,754)	(36,723)	(36,376)
Current liabilities:
Current maturities of long-term debt		75,000
Total current liabilities		75,000
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net		23,931	24,754	36,723	34,276
Total deferred income taxes and other credits		23,931	24,754	36,723	34,276
Total capitalization and liabilities		$ 0	$ 0	$ 0	$ (2,100)

Common Stock (Details) - USD ($) shares in Thousands		12 Months Ended
Common Stock (Details) - USD ($) shares in Thousands	Aug. 06, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Common stock issued, amount		$ 37,276,000	$ 21,579,000	$ 259,002,000
Shares registered and available for issuance (in shares)		5,000
Omnibus Incentive Plan and Restricted Stock/Unit Plan
Class of Stock [Line Items]
Common stock issued (in shares)		186
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued (in shares)		256
Common stock issued, amount		$ 19,200,000
ATM Program
Class of Stock [Line Items]
Aggregate net proceeds from stock offering	$ 340,000,000

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

Pension and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan, payment term, option one	10 years
Deferred compensation plan, payment term, option two	15 years
Deferred compensation plan, payment term, option three	20 years
Defined benefit plan, funded percentage	102.00%
Future estimated funding amount	$ 23.5
Defined Benefit Plan, Equity Securities And Fixed Income Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage				95.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets allocation, percentage				45.00%
Fixed Income Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets allocation, percentage				55.00%
Defined benefit plan, plan assets, target allocation, percentage	25.00%
Maximum \| Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	75.00%
Minimum \| Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	25.00%
QRP
Defined Benefit Plan Disclosure [Line Items]
Future estimated funding amount	$ 20.0
PBOP \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Per capita cost of covered health care benefits medical rate trend assumption	5.00%
PBOP \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Per capita cost of covered health care benefits medical rate trend assumption	4.50%
Southwest Gas Corporation
Defined Benefit Plan Disclosure [Line Items]
Employees' investment plan, percent of compensation deferred with match	50.00%
Employees' investment plan, employer matching contribution, percent of match	3.00%
Employees' investment plan, employer matching contribution, percent of employees' eligible compensation	7.00%
Employee investment plan cost	$ 12.2	$ 9.9	$ 8.3
Deferred compensation plan, maximum percentage of salary deferral	100.00%
Deferred compensation plan, matching percentage	3.50%
Deferred compensation plan, percent of amount deferred with match	50.00%
Period of additional option to receive payment	5 years
Deferred compensation, percentage of multiple interest rate	150.00%
Southwest Gas Corporation \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Employees' investment plan, employer matching contribution, percent of match	3.50%

CONSOLIDATED STATEMENTS OF INCOME - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating revenues:
Regulated operations revenues	$ 1,940,380	$ 2,475,216	$ 2,534,696
Operating expenses:
Net cost of gas sold	497,636	1,150,005	1,253,269
Operations and maintenance	544,064	526,679	533,009
Depreciation and amortization	330,724	303,095	295,462
Taxes other than income taxes	94,070	88,965	88,751
Total operating expenses	1,466,494	2,068,744	2,241,721
Operating income	473,886	406,472	292,975
Other income and (expenses):
Net interest deductions	(203,081)	(206,528)	(194,810)
Other income (deductions)	60,068	54,192	71,239
Total other income and (expenses)	(143,013)	(152,336)	(123,571)
Income from continuing operations before income taxes	330,873	254,136	169,404
Income tax expense	96,037	33,157	29,410
Net income	439,826	198,815	150,889
Southwest Gas Corporation
Operating revenues:
Regulated operations revenues	1,942,480	2,482,990	2,494,220
Operating expenses:
Net cost of gas sold	497,636	1,157,364	1,251,367
Operations and maintenance	537,644	520,820	510,387
Depreciation and amortization	330,724	303,095	295,462
Taxes other than income taxes	94,070	88,965	87,261
Total operating expenses	1,460,074	2,070,244	2,144,477
Operating income	482,406	412,746	349,743
Other income and (expenses):
Net interest deductions	(181,677)	(162,257)	(149,830)
Other income (deductions)	52,402	54,276	70,661
Total other income and (expenses)	(129,275)	(107,981)	(79,169)
Income from continuing operations before income taxes	353,131	304,765	270,574
Income tax expense	52,823	42,669	42,162
Net income	$ 300,308	$ 262,096	$ 228,412

Income Taxes - Narrative (Details) $ in Millions	Dec. 31, 2025 USD ($)
Federal
Income Tax Disclosure [Line Items]
Operating loss carryforward	$ 599.4
State:
Income Tax Disclosure [Line Items]
Operating loss carryforward	$ 435.7

Regulatory Assets and Liabilities

12 Months Ended

Dec. 31, 2025

Regulatory Assets and Liabilities

Note 5 - Regulatory Assets and Liabilities

Southwest Gas is subject to the regulation of the ACC, the PUCN, the CPUC, and the FERC. Accounting policies for Southwest Gas conform to U.S. GAAP applicable to rate-regulated entities and reflect the effects of the ratemaking process. Accounting treatment for rate-regulated entities allows for deferral as regulatory assets, costs that otherwise would be expensed, if it is probable that future recovery from customers will occur. If rate recovery is no longer probable, due to competition or the actions of regulators, the related regulatory asset is required to be written off. Regulatory liabilities are recorded if it is probable that revenues will be reduced for amounts that will be refunded to customers through the ratemaking process. Management records regulatory assets and liabilities based on decisions of the commissions noted above, including the issuance of regulatory orders and precedents established by these commissions. Southwest Gas has generally been successful in seeking recovery of regulatory assets and regularly files rate cases or other administrative filings in the various jurisdictions, in some cases, to establish the basis for recovering regulatory assets reflected in accounting records.


	December 31,
(Thousands of dollars)	2025		2024
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	246,444	$	299,961
Deferred purchased gas costs (2)	5,214		13,807
Unamortized premium on reacquired debt (3)	10,016		11,529
Accrued absence time (4)	22,430		21,231
Margin, interest- and property tax-tracking (5)	142,813		57,477
Other (9)	92,820		90,083
Total regulatory assets	$	519,737	$	494,088
Regulatory liabilities:
Deferred purchased gas costs (2),(10)	(310,085)		(255,398)
Accumulated removal costs (6)	(496,000)		(472,000)
Unamortized gain on reacquired debt (7)	(4,963)		(5,500)
Regulatory excess deferred/other taxes and gross-up (8)	(348,243)		(363,353)
Margin, interest- and property tax-tracking (5)	(26,019)		(25,112)
Other (9)	(10,374)		(3,465)
Total regulatory liabilities	(1,195,684)		(1,124,828)
Net regulatory assets (liabilities) (11)	$	(675,947)	$	(630,740)

(1) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 10 - Pension and Other Postretirement Benefits).

(2) Balance recovered or refunded on an ongoing basis with interest.

(3) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(4) Recovery through cost of service generally on a one-year lag basis and part of overhead loading processes. Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(7) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets; amortized over life of debt instruments.

(10) Deferred purchased gas costs as of December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.

(11) Net regulatory assets (liabilities) for the year ended December 31, 2024 differs from Southwest Gas due to the revision discussed in Note 3 - Revision of Previously Issued Financial Statements.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (f)	$	21,308	$	24,404
Infrastructure replacement programs and similar (b) (f)	32,516		24,262
Environmental compliance programs (c) (f)	7,087		3,730
Pension tracking mechanism (d)	16,727		16,151
Other (e)	15,182		21,536
	$	92,820	$	90,083

(a) Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(b) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(d) Included in Deferred charges and other assets on the Consolidated Balance Sheets.

(f) Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
(Thousands of dollars)	2025		2024
Other Regulatory Liabilities:

Infrastructure replacement programs and similar (g)	$	(2,484)	$	(2,069)
Environmental compliance programs (g) (h)	(6,710)		(733)

Other (h) (i)	(1,180)		(663)
	$	(10,374)	$	(3,465)

(g) Included in Other current liabilities on the Consolidated Balance Sheets.

(h) Balance typically recovered or refunded on an ongoing basis, generally with interest.

(i) Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

Regulatory Assets/Liabilities Not Earning a Return

•Regulatory assets/liabilities related to accrued pension and other postretirement benefit costs are offset by corresponding liabilities/assets. The assets are recovered in rates as the plans are funded.

•Margin-related mechanisms exist in various forms in each of the Company’s regulatory jurisdictions. Balances related to the decoupling mechanisms in Nevada do not earn a return. Recovery rates are designed to recover the outstanding balances over a twelve-month period.

Regulatory Assets/Liabilities Earning a Return

•Over- and undercollected regulatory balancing accounts and other regulatory assets, net, reflect the difference between customer billings and recorded or authorized by the ACC, CPUC, PUCN, or FERC. Depreciation, taxes and return on rate base may also be included in certain accounts. Amounts in the balancing accounts are recoverable (receivable) or refundable (payable) in future rates, subject to ACC, CPUC, PUCN, or FERC approval. These relate to the following:

▪The following mechanisms earn a return on based on the monthly one-year nominal Treasury Constant Maturities for Arizona and Commercial Paper for California and are generally designed to address the outstanding balances over a twelve-month period:

•Deferred purchased gas cost

•Margin-related mechanisms

•State mandated public purpose programs

▪The following mechanisms are revenue requirement and earn the authorized rate of return per the general rate cases for the applicable jurisdiction:

•Deferred purchased gas cost - Nevada

•Unamortized premium on reacquired debt

•Accrued absence time

•Interest-tracking mechanism

•Property tax-tracking mechanisms

•Accumulated removal costs

•Unamortized gain on reacquired debt

•Regulatory excess deferred/other taxes and gross-up mechanism

•Pension tracking mechanism

▪Infrastructure replacement programs vary by jurisdiction and program type.

Regulated Operations Plant - Schedule of Regulated Operations Plant (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	$ 11,517,031	$ 10,844,895
Less: accumulated depreciation and amortization	(3,063,363)	(2,914,457)
Construction work in progress	236,871	178,647
Net regulated operations plant	8,690,539	8,109,085
Storage
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	122,543	121,817
Transmission
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	461,260	447,719
Distribution
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	9,940,646	9,343,955
General
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	623,303	587,423
Software and software-related
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	354,567	328,769
Other
Public Utility, Property, Plant and Equipment [Line Items]
Total gas plant	$ 14,712	$ 15,212

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of Other Property and Investments

Other property and investments on Southwest Gas’ and the Company’s Consolidated Balance Sheets include:


	December 31,
(Thousands of dollars)	2025		2024
Net cash surrender value of COLI policies	$	165,551	$	155,199
Other property	4,396		4,479
Total Southwest Gas Corporation	169,947		159,678


Other property and investments	8,879		5,770
Total Southwest Gas Holdings, Inc.	$	178,826	$	165,448

Schedule of Capitalized and Debt Portion of AFUDC

Regulated operations plant construction costs, including AFUDC, are recoverable as part of authorized rates through depreciation when completed projects are placed into operation and general rate relief is requested and granted. AFUDC, disaggregated by type, included in the Company’s and Southwest Gas’ Consolidated Statements of Income are presented in the table below:


(Thousands of dollars)	2025			2024			2023
AFUDC:
Debt portion	$	2,707		$	3,126		$	6,851
Equity portion(1)	5,809			6,597			1,951
AFUDC capitalized as part of regulated operations plant	$	8,516		$	9,723		$	8,802
AFUDC rate	6.77		%	6.76		%	6.30		%

(1)Equity AFUDC for the year ended December 31, 2023 includes MountainWest activity.

Schedule of Other Income (Deductions)

The following table provides the composition of significant items included in Other income (deductions) on the Consolidated Statements of Income:


(Thousands of dollars)	2025		2024		2023
Southwest Gas Corporation:
Change in COLI policies	$	10,300	$	8,400	$	10,100
Interest income	20,944		33,581		50,757
Equity AFUDC	5,809		6,597		1,869
Non-service components of net periodic benefit cost	17,475		16,523		20,387
Miscellaneous expense	(2,126)		(10,825)		(12,452)
Southwest Gas Corporation – total other income (deductions)	52,402		54,276		70,661
Southwest Gas Holdings, Inc.:
Equity AFUDC	—		—		82
Equity in earnings of unconsolidated investments	—		—		394
Miscellaneous income and (expense)	—		—		(49)
Corporate and administrative	7,666		(84)		151
Southwest Gas Holdings, Inc. - total other income (deductions)	$	60,068	$	54,192	$	71,239

Schedule of Earnings Per Share, Basic and Diluted

A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table:


(In thousands)	2025	2024	2023
Weighted average basic shares	72,162	71,841	70,787
Effect of dilutive securities:
Restricted stock units (1)(2)	175	191	203
Weighted average diluted shares	72,337	72,032	70,990

(2) The number of anti-dilutive restricted stock units excluded from the calculation of diluted shares from discontinued operations in 2024 is 191,000.

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Less: current maturities	$ 75,000	$ 75,000	$ 0
Long-term debt, less current maturities	$ 3,433,012	$ 3,432,120	3,504,477
Debentures \| 8% Series, due 2026
Debt Instrument [Line Items]
Debt instrument interest rate	8.00%
Long-term debt, gross	$ 75,000
Debentures \| Medium-term notes, 7.92% series, due 2027
Debt Instrument [Line Items]
Debt instrument interest rate	7.92%
Debentures \| Medium-term notes, 6.76% series, due 2027
Debt Instrument [Line Items]
Debt instrument interest rate	6.76%
Debentures \| Notes, 5.8%, due 2027
Debt Instrument [Line Items]
Debt instrument interest rate	5.80%
Debentures \| Notes, 3.7%, due 2028
Debt Instrument [Line Items]
Debt instrument interest rate	3.70%
Debentures \| Notes, 5.45%, due 2028
Debt Instrument [Line Items]
Debt instrument interest rate	5.45%
Debentures \| Notes, 2.2%, due 2030
Debt Instrument [Line Items]
Debt instrument interest rate	2.20%
Debentures \| Notes, 4.05%, due 2032
Debt Instrument [Line Items]
Debt instrument interest rate	4.05%
Debentures \| Notes, 6.1%, due 2041
Debt Instrument [Line Items]
Debt instrument interest rate	6.10%
Debentures \| Notes, 4.875%, due 2043
Debt Instrument [Line Items]
Debt instrument interest rate	4.875%
Debentures \| Notes, 3.8%, due 2046
Debt Instrument [Line Items]
Debt instrument interest rate	3.80%
Debentures \| Notes, 4.15%, due 2049
Debt Instrument [Line Items]
Debt instrument interest rate	4.15%
Debentures \| Notes, 3.18%, due 2051
Debt Instrument [Line Items]
Debt instrument interest rate	3.18%
Carrying Amount
Debt Instrument [Line Items]
Less: current maturities	$ 75,000		0
Long-term debt, less current maturities	3,433,012		3,504,477
Carrying Amount \| Debentures
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(23,207)		(26,477)
Total	3,309,293		3,306,023
Carrying Amount \| Debentures \| 8% Series, due 2026
Debt Instrument [Line Items]
Long-term debt, gross	75,000		75,000
Carrying Amount \| Debentures \| Medium-term notes, 7.92% series, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	25,000		25,000
Carrying Amount \| Debentures \| Medium-term notes, 6.76% series, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	7,500		7,500
Carrying Amount \| Debentures \| Notes, 5.8%, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 3.7%, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 5.45%, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 2.2%, due 2030
Debt Instrument [Line Items]
Long-term debt, gross	450,000		450,000
Carrying Amount \| Debentures \| Notes, 4.05%, due 2032
Debt Instrument [Line Items]
Long-term debt, gross	600,000		600,000
Carrying Amount \| Debentures \| Notes, 6.1%, due 2041
Debt Instrument [Line Items]
Long-term debt, gross	125,000		125,000
Carrying Amount \| Debentures \| Notes, 4.875%, due 2043
Debt Instrument [Line Items]
Long-term debt, gross	250,000		250,000
Carrying Amount \| Debentures \| Notes, 3.8%, due 2046
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 4.15%, due 2049
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 3.18%, due 2051
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Industrial development revenue bonds
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(1,281)		(1,546)
Total	198,719		198,454
Carrying Amount \| Industrial development revenue bonds \| Tax-exempt Series A, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2003 Series A, due 2038
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2008 Series A, due 2038
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2009 Series A, due 2039
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Debentures \| 8% Series, due 2026
Debt Instrument [Line Items]
Long-term debt, gross	76,388		77,898
Fair Value \| Debentures \| Medium-term notes, 7.92% series, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	26,058		26,285
Fair Value \| Debentures \| Medium-term notes, 6.76% series, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	7,726		7,701
Fair Value \| Debentures \| Notes, 5.8%, due 2027
Debt Instrument [Line Items]
Long-term debt, gross	309,090		306,450
Fair Value \| Debentures \| Notes, 3.7%, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	297,450		287,460
Fair Value \| Debentures \| Notes, 5.45%, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	307,620		302,970
Fair Value \| Debentures \| Notes, 2.2%, due 2030
Debt Instrument [Line Items]
Long-term debt, gross	409,365		385,425
Fair Value \| Debentures \| Notes, 4.05%, due 2032
Debt Instrument [Line Items]
Long-term debt, gross	579,540		558,120
Fair Value \| Debentures \| Notes, 6.1%, due 2041
Debt Instrument [Line Items]
Long-term debt, gross	130,762		127,900
Fair Value \| Debentures \| Notes, 4.875%, due 2043
Debt Instrument [Line Items]
Long-term debt, gross	219,350		210,700
Fair Value \| Debentures \| Notes, 3.8%, due 2046
Debt Instrument [Line Items]
Long-term debt, gross	228,180		219,390
Fair Value \| Debentures \| Notes, 4.15%, due 2049
Debt Instrument [Line Items]
Long-term debt, gross	237,120		223,470
Fair Value \| Debentures \| Notes, 3.18%, due 2051
Debt Instrument [Line Items]
Long-term debt, gross	205,710		187,680
Fair Value \| Industrial development revenue bonds \| Tax-exempt Series A, due 2028
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2003 Series A, due 2038
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2008 Series A, due 2038
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2009 Series A, due 2039
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000		$ 50,000

Revision of Previously Issued Financial Statements - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Equity (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 4,088,534		$ 3,681,422	$ 3,681,422	$ 3,310,036	$ 3,058,759
Net income (loss)	262,634	$ (40,154)		439,826	198,815	150,889
Ending balance	3,893,566	4,088,534		3,961,119	3,681,422	3,310,036
Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,383,619	3,380,149	3,235,486	3,235,486	3,146,319	2,545,693
Net income (loss)	6,343	45,646	142,595	300,308	262,096	228,412
Ending balance	3,392,532	3,383,619	3,380,149	3,524,966	3,235,486	3,146,319
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	742,452		758,649	758,649	738,839	747,069
Net income (loss)				439,826	198,815	150,889
Ending balance	964,286	742,452		1,022,846	758,649	738,839
Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,203,006	1,202,052	1,059,773	1,059,773	981,178	911,873
Net income (loss)				300,308	262,096	228,412
Ending balance	1,209,265	1,203,006	1,202,052	1,314,911	1,059,773	981,178
As Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	4,115,805
Net income (loss)	270,476	(12,883)
Ending balance	3,928,679	4,115,805
As Reported \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,408,373	3,416,872	3,271,862	3,271,862	3,183,615	2,569,175
Net income (loss)	5,520	33,677	142,942		261,176	242,226
Ending balance	3,416,463	3,408,373	3,416,872		3,271,862	3,183,615
As Reported \| Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	769,723
Ending balance	999,399	769,723
As Reported \| Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,227,760	1,238,775	1,096,149	1,096,149	1,018,474	935,355
Ending balance	1,233,196	1,227,760	1,238,775		1,096,149	1,018,474
Adjustments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(27,271)
Net income (loss)	(7,842)	(27,271)
Ending balance	(35,113)	(27,271)
Adjustments \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(24,754)	(36,723)	(36,376)	(36,376)	(37,296)	(23,482)
Net income (loss)	823	11,969	(347)		920	(13,814)
Ending balance	(23,931)	(24,754)	(36,723)		(36,376)	(37,296)
Adjustments \| Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(27,271)
Ending balance	(35,113)	(27,271)
Adjustments \| Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(24,754)	(36,723)	(36,376)	$ (36,376)	(37,296)	(23,482)
Ending balance	$ (23,931)	$ (24,754)	$ (36,723)		$ (36,376)	$ (37,296)

Amount of equity (deficit) attributable to parent and noncontrolling interest. Excludes temporary equity.

Pension and Other Postretirement Benefits - Schedule of Asset Return Assumption (Details)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Southwest Gas Corporation
Defined Benefit Plan Disclosure [Line Items]
Asset return assumption	7.00%	7.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in USD per share)	$ 2.48	$ 2.48	$ 2.48

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net actuarial gain (loss), tax expense (benefit)	$ 13,114	$ 1,162	$ (765)
Amortization of prior service cost, tax expense	42	42	42
Amortization of net actuarial loss, tax expense	906	1,834	319
Regulatory adjustment, tax benefit	$ (12,844)	$ (2,360)	$ (319)

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$ 78,826	$ 81,802
Net operating losses	146,287	144,172
Other	3,848	2,107
Valuation allowance	0	(1,117)
Total deferred tax assets	228,961	226,964
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822	1,020,885
Regulatory balancing accounts	1,459	3,988
Debt-related costs	1,055	1,384
Employee benefits	29,680	24,118
Other	54,257	34,571
Total deferred tax liabilities	1,206,273	1,084,946
Net deferred tax liabilities	977,312	857,982
Southwest Gas Corporation
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	78,826	81,802
Net operating losses	89,174	188,458
Other	3,258	2,543
Total deferred tax assets	171,258	272,803
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822	1,064,187
Regulatory balancing accounts	1,459	4,157
Debt-related costs	1,055	1,443
Employee benefits	31,865	27,337
Other	44,978	29,928
Total deferred tax liabilities	1,199,179	1,127,052
Net deferred tax liabilities	$ 1,027,921	$ 854,249

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 435,180	$ 204,836	$ 155,517
Defined benefit pension plans:
Net actuarial gain (loss), net of tax expense (benefit) of $13,114, $1,162 and $(765), respectively	41,526	3,680	(2,423)
Amortization of prior service cost, net of tax expense of $42, $42 and $42, respectively	133	133	133
Amortization of net actuarial loss, net of tax expense of $906, $1,834 and $319, respectively	2,869	5,807	1,014
Regulatory adjustment, net of tax benefit of $(12,844), $(2,360) and $(319), respectively	(40,673)	(7,473)	(1,011)
Net defined benefit pension plans, net of tax	3,855	2,147	(2,287)
Other comprehensive income (loss) related to discontinued operations	5,153	(10,123)	2,742
Total other comprehensive income (loss), net of tax	9,008	(7,976)	455
Comprehensive income	444,188	196,860	155,972
Comprehensive income (loss) attributable to noncontrolling interests	(4,357)	4,680	4,628
Comprehensive income attributable to Southwest Gas Holdings, Inc.	$ 448,545	$ 192,180	$ 151,344

Receivables and Related Allowances - Schedule of Percent of Customers by State (Details)	12 Months Ended
	Dec. 31, 2025 state
Receivables And Related Allowances [Line Items]
Number of states in which entity operates	3
ARIZONA
Receivables And Related Allowances [Line Items]
Percent of customers by state	54.00%
Nevada
Receivables And Related Allowances [Line Items]
Percent of customers by state	37.00%
California
Receivables And Related Allowances [Line Items]
Percent of customers by state	9.00%

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Regulated operations plant:
Gas plant	$ 11,517,031	$ 10,844,895
Less: accumulated depreciation	(3,063,363)	(2,914,457)
Construction work in progress	236,871	178,647
Net regulated operations plant	8,690,539	8,109,085
Other property and investments, net	178,826	165,448
Current assets:
Cash and cash equivalents	576,645	314,770
Accounts receivable, net of allowances	170,601	203,012
Accrued utility revenue	101,600	96,600
Income taxes receivable, net	9,611	0
Deferred purchased gas costs	5,214	13,807
Materials, supplies & gas inventories	93,823	93,755
Prepaid and other current assets	234,598	141,017
Current assets classified as discontinued operations	0	601,384
Total current assets	1,192,092	1,464,345
Noncurrent assets:
Goodwill	11,155	11,155
Deferred charges and other assets	356,865	395,747
Noncurrent assets classified as discontinued operations	0	1,927,126
Total noncurrent assets	368,020	2,334,028
Total assets	10,429,477	12,072,906
Capitalization:
Common stock, $1 par (authorized – 120,000,000 shares; issued and outstanding – 72,224,593 and 71,782,756 shares)	73,854	73,413
Additional paid-in capital	2,898,965	2,721,343
Accumulated other comprehensive loss, net	(34,546)	(49,218)
Retained earnings	1,022,846	758,649
Total equity attributable to Southwest Gas Holdings, Inc. stockholders	3,961,119	3,504,187
Noncontrolling interest	0	177,235
Total equity	3,961,119	3,681,422
Redeemable noncontrolling interest	0	7,660
Long-term debt, less current maturities	3,433,012	3,504,477
Total capitalization	7,394,131	7,193,559
Commitments and contingencies (Note 15)
Current liabilities:
Current maturities of long-term debt	75,000	0
Short-term debt	0	680,000
Accounts payable	225,732	190,918
Customer deposits	67,249	63,876
Accrued general taxes	54,384	59,353
Accrued interest	35,319	35,668
Deferred purchased gas costs	310,085	255,398
Dividends declared	44,779	44,505
Other current liabilities	117,350	119,357
Current liabilities of discontinued operations	0	382,892
Total current liabilities	929,898	1,831,967
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	977,312	857,982
Accumulated removal costs	496,000	472,000
Other deferred credits and other long-term liabilities	632,136	700,672
Noncurrent liabilities classified as discontinued operations	0	1,016,726
Total deferred income taxes and other credits	2,105,448	3,047,380
Total capitalization and liabilities	$ 10,429,477	$ 12,072,906

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

Note 11 - Income Taxes

Southwest Gas Holdings, Inc.:

The following is a summary of income before taxes from continuing operations:


	Year ended December 31,
(Thousands of dollars)	2025		2024		2023
Income from continuing operations before income taxes	$	330,873	$	254,136	$	169,404

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Current:
Federal	$	(24)	$	1,289	$	(66)
State	1,777		570		402
Total current tax expense	1,753		1,859		336
Deferred:
Federal	55,547		28,627		19,400
State	38,737		2,671		9,674
Total deferred tax expense	94,284		31,298		29,074
Total income tax expense	$	96,037	$	33,157	$	29,410


	Year Ended December 31,
	2025				2024				2023
(Thousands of dollars)	Amount		Percent		Amount		Percent		Amount		Percent
U.S. federal statutory income tax	$	69,483	21.0	%	$	53,369	21.0	%	$	35,575	21.0	%
State and local income tax, net of deferred benefit (1)	40,515		12.2	%	3,230		1.2	%	9,420		5.6	%
Tax credits	(2,213)		(0.6)	%	(1,716)		(0.7)	%	(440)		(0.3)	%
Changes in valuation allowance	—		—		1,032		0.4	%	—		—
Nontaxable and nondeductible items:
Corporate-owned life insurance	(2,242)		(0.7)	%	(1,842)		(0.7)	%	(2,196)		(1.3)	%
Other	848		0.3	%	589		0.2	%	197		0.1	%
Changes in unrecognized tax benefits	(182)		(0.1)	%	(1,849)		(0.7)	%	(23)		—	%
Other adjustments:
Amortization of excess deferred taxes	(10,172)		(3.1)	%	(19,656)		(7.7)	%	(23,112)		(13.6)	%
MountainWest sale	—		—		—		—		9,989		5.9	%
Total income tax expense and effective income tax rate	$	96,037	29.0	%	$	33,157	13.0	%	$	29,410	17.4	%

(1) State taxes in Arizona made up the majority (greater than 50%) of the tax effect in this category. In addition, this reflects the impact of the revised state apportionment rates recorded in 2025.

Total cash paid for income taxes, net of refunds, are detailed below. Please note that the table below includes totals for both continuing and discontinued operations.


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Federal	$	24,500	$	(350)	$	(2,421)
State:
California	8,502		—		—
Illinois	2,060		—		—
Indiana	—		509		—
Maryland	—		1,104		—
Massachusetts	—		512		—
Pennsylvania	—		—		837
Texas	—		—		723
Other states	4,197		800		1,045
Canada	1,229		7,330		9,181
Total income taxes paid, net	$	40,488	$	9,905	$	9,365

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2025		2024
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	78,826	$	81,802
Net operating losses	146,287		144,172
Other	3,848		2,107
Valuation allowance	—		(1,117)
Total deferred tax assets	228,961		226,964
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822		1,020,885
Regulatory balancing accounts	1,459		3,988
Debt-related costs	1,055		1,384
Employee benefits	29,680		24,118
Other	54,257		34,571
Total deferred tax liabilities	1,206,273		1,084,946
Net noncurrent deferred tax liabilities	$	977,312	$	857,982

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2025		2024
Unrecognized tax benefits at beginning of year	$	773	$	2,622
Gross increases – tax positions in prior period	95		83
Gross increases – current period tax positions	—		171
Gross decreases – current period tax positions	(277)		—
Lapse in statute of limitations	—		(2,103)
Unrecognized tax benefits at end of year	$	591	$	773

At December 31, 2025, the Company has a U.S. federal net operating loss carryforward of $599.4 million on a tax return basis. As of the same date, the Company has $435.7 million of state net operating loss carryforwards on a tax return basis. Depending on the jurisdiction in which the state net operating loss was generated, the carryforwards will begin to expire in 2041.

Southwest Gas Corporation:

Certain amounts in this disclosure have been revised as discussed in Note 3 - Revision of Previously Issued Financial Statements.

The following is a summary of income before taxes:


	Year ended December 31,
(Thousands of dollars)	2025		2024		2023
Total income before income taxes	$	353,131	$	304,765	$	270,574

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Current:
Federal	$	(96,017)	$	(12)	$	(21)
State	(9,051)		105		98
Total current tax expense	(105,068)		93		77
Deferred:
Federal	156,138		39,730		30,980
State	1,753		2,846		11,105
Total deferred tax expense	157,891		42,576		42,085
Total income tax expense	$	52,823	$	42,669	$	42,162

A reconciliation of the U.S. federal statutory rate to the Southwest Gas effective income tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2025				2024				2023
(Thousands of dollars)	Amount		Percent		Amount		Percent		Amount		Percent
U.S. federal statutory income tax	$	74,157	21.0	%	$	64,001	21.0	%	$	56,821	21.0	%
State and local income tax, net of deferred benefit (1)	(7,298)		(2.1)	%	2,946		1.0	%	10,773		4.0	%
Tax credits	(2,213)		(0.6)	%	(1,716)		(0.6)	%	(440)		(0.2)	%

Nontaxable and nondeductible items	(1,470)		(0.3)	%	(1,057)		(0.3)	%	(2,100)		(0.7)	%
Changes in unrecognized tax benefits	(182)		(0.1)	%	(1,849)		(0.6)	%	(23)		—	%
Other adjustments:
Amortization of excess deferred taxes	(10,171)		(2.9)	%	(19,656)		(6.5)	%	(22,869)		(8.5)	%
Total income tax expense and effective income tax rate	$	52,823	15.0	%	$	42,669	14.0	%	$	42,162	15.6	%

(1) State taxes in Arizona made up the majority (greater than 50%) of the tax effect in this category. In addition, this reflects the impact of the revised state apportionment rates recorded in 2025.

Income taxes paid, net of refunds, are as follows:


	Year Ended December 31,
(Thousands of dollars)	2025		2024		2023
Federal	$	585	$	—	$	—
California	421		—		—
Total income taxes paid, net	$	1,006	$	—	$	—

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2025		2024
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	78,826	$	81,802
Net operating losses	89,174		188,458
Other	3,258		2,543
Total deferred tax assets	171,258		272,803
Deferred tax liabilities:
Property-related items, including accelerated depreciation	1,119,822		1,064,187
Regulatory balancing accounts	1,459		4,157
Debt-related costs	1,055		1,443
Employee benefits	31,865		27,337
Other	44,978		29,928
Total deferred tax liabilities	1,199,179		1,127,052
Net deferred tax liabilities	$	1,027,921	$	854,249

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2025		2024
Unrecognized tax benefits at beginning of year	$	773	$	2,622
Gross increases – tax positions in prior period	95		83
Gross increases – current period tax positions	—		171
Gross decreases – current period tax positions	(277)		—
Lapse in statute of limitations	—		(2,103)
Unrecognized tax benefits at end of year	$	591	$	773

Southwest Gas Holdings, Inc. and Southwest Gas Corporation:

In assessing whether uncertain tax positions should be recognized in its financial statements, management first determines whether it is more-likely-than-not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. In evaluations of whether a tax position has met the more-likely-than-not recognition threshold, management presumes that the position will be examined by the appropriate taxing authority that would have full knowledge of all relevant information. For tax positions that meet the more-likely-than-not recognition threshold, management measures the amount of benefit recognized in the financial statements at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. Unrecognized tax benefits are recognized in the first financial reporting period in which information becomes available indicating that such benefits will more-likely-than-not be realized. For each reporting period, management applies a consistent methodology to measure unrecognized tax benefits, and all unrecognized tax benefits are reviewed periodically and adjusted as circumstances warrant. Measurement of unrecognized tax benefits is based on management’s assessment of all relevant information, including prior audit experience, the status of audits, conclusions of tax audits, lapsing of applicable statutes of limitation, identification of new issues, and any administrative guidance or developments.

The Company and Southwest Gas recognize interest expense and penalties related to income tax matters in income tax expense. The amount of tax-related interest income for 2023 through 2025 was not significant.

The Company and its subsidiaries file a consolidated federal income tax return in the U.S. and in various states. With few exceptions, the Company is no longer subject to U.S. federal, state and local income tax examinations for years before 2021.

The Company and each of its subsidiaries, including Southwest Gas, participate in a tax sharing agreement to establish the method for allocating tax benefits and losses among members of the consolidated group. The consolidated federal income tax is apportioned among the subsidiaries using a separate return method. According to the terms of the tax sharing agreement, the Company will pay Southwest Gas for the tax attributes that will be utilized in 2025 (primarily used to offset the taxable gain on the sale of Centuri).

In April 2023, the IRS issued Revenue Procedure 2023-15, which provides a safe harbor method of accounting that taxpayers may use to determine whether expenditures to repair, maintain, replace, or improve natural gas transmission and distribution property must be capitalized for tax purposes. Southwest Gas adopted this change in tax accounting method with its 2024 U.S. federal income tax return filing in 2025, and the safe harbor method increased the total tax repair deductions. Southwest Gas Holdings, Inc. and Southwest Gas’ deferred taxes reflect the impacts of this adoption and are not material to the consolidated financial statements overall.

The entire disclosure for income tax.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Debt

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Debt

Note 9 - Debt

Long-Term Debt

Long-term debt is recognized in the Company’s and Southwest Gas’ Consolidated Balance Sheets generally at the carrying value of the obligations outstanding. Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows.


	December 31,
	2025				2024
(Thousands of dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Southwest Gas Holdings, Inc. and Southwest Gas Corporation:
Debentures:
8% Series, due 2026	$	75,000	$	76,388	$	75,000	$	77,898
Medium-term notes, 7.92% series, due 2027	25,000		26,058		25,000		26,285
Medium-term notes, 6.76% series, due 2027	7,500		7,726		7,500		7,701
Notes, 5.8%, due 2027	300,000		309,090		300,000		306,450
Notes, 3.7%, due 2028	300,000		297,450		300,000		287,460
Notes, 5.45%, due 2028	300,000		307,620		300,000		302,970
Notes, 2.2%, due 2030	450,000		409,365		450,000		385,425
Notes, 4.05%, due 2032	600,000		579,540		600,000		558,120
Notes, 6.1%, due 2041	125,000		130,762		125,000		127,900
Notes, 4.875%, due 2043	250,000		219,350		250,000		210,700
Notes, 3.8%, due 2046	300,000		228,180		300,000		219,390
Notes, 4.15%, due 2049	300,000		237,120		300,000		223,470
Notes, 3.18%, due 2051	300,000		205,710		300,000		187,680
Unamortized discount and debt issuance costs	(23,207)				(26,477)
	3,309,293				3,306,023

Industrial development revenue bonds:
Tax-exempt Series A, due 2028	50,000		50,000		50,000		50,000
2003 Series A, due 2038	50,000		50,000		50,000		50,000
2008 Series A, due 2038	50,000		50,000		50,000		50,000
2009 Series A, due 2039	50,000		50,000		50,000		50,000
Unamortized discount and debt issuance costs	(1,281)				(1,546)
	198,719				198,454
Less: current maturities	75,000				—
Southwest Gas Holdings, Inc. and Southwest Gas Corporation total long-term debt, less current maturities	$	3,433,012			$	3,504,477

The fair values of the Company’s revolving credit facilities and IDRBs are estimated using observable market inputs, including current interest rates and are therefore classified as Level 2 in the hierarchy. The fair values of Southwest Gas’ debentures (which include senior and medium-term notes) were determined utilizing a market-based valuation approach, where fair values are determined based on observable trading data and as such are categorized as Level 2 in the hierarchy.

Southwest Gas has a $400.0 million credit facility scheduled to expire in August 2029. Southwest Gas designates $150.0 million of associated capacity as long-term debt and the remaining $250.0 million for working capital purposes. In June 2025, Southwest Gas amended this revolving credit agreement, which, among other things, added a swingline loan sub-facility in an aggregate principal amount at any time outstanding not to exceed $30.0 million and added a one-week interest period option with an interest rate equal to Daily Simple SOFR plus 0.03839% plus the applicable margin. At December 31, 2025, the applicable margin was 1.125% for loans bearing interest with reference to SOFR and 0.125% for loans bearing interest with reference to the alternative base rate. Southwest Gas is also required to pay a commitment fee on the unfunded portion of the commitments which ranges from 0.075% to 0.200%. At December 31, 2025, no borrowings were outstanding on the long-term portion (including under the commercial paper program discussed below) nor under the short-term portion of the facility.

Southwest Gas has a $50.0 million commercial paper program. Issuances under the commercial paper program are supported by Southwest Gas’ current revolving credit facility and therefore do not represent additional borrowing capacity. Borrowings under the commercial paper program, if any, are designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At December 31, 2025, no borrowings were outstanding under the commercial paper program.

The effective interest rates on Southwest Gas’ variable-rate IDRBs are included in the table below:


	December 31,
	2025		2024
2003 Series A	3.50	%	4.86	%
2008 Series A	3.84	%	4.89	%
2009 Series A	3.75	%	4.73	%
Tax-exempt Series A	3.10	%	4.29	%

In Nevada, interest fluctuations due to changing interest rates on Southwest Gas’ 2003 Series A, 2008 Series A, and 2009 Series A variable-rate IDRBs are tracked and recovered from customers through a variable interest expense recovery mechanism.

None of Southwest Gas’ debt instruments have credit triggers or other clauses that result in default if bond ratings are lowered by rating agencies. Interest and fees on certain debt instruments are subject to adjustment depending on Southwest Gas’ bond ratings. Certain debt instruments are subject to a leverage ratio cap, and the 6.1% Notes due 2041 are also subject to a minimum net worth requirement. At December 31, 2025, Southwest Gas was in compliance with all of its covenants. Under the most restrictive of the financial covenants, approximately $4.7 billion in additional debt could be issued while still meeting the leverage ratio requirement. Relating to the minimum net worth requirement, as of December 31, 2025, there is approximately $3.0 billion of cushion in equity. No specific dividend restrictions exist under the collective covenants. None of the debt instruments contain material adverse change clauses.

Estimated maturities of long-term debt and the current portion of long-term debt for the next five years are:


(Thousands of dollars)	2026		2027		2028		2029		2030
Southwest Gas Holdings, Inc. and Southwest Gas Corporation:
Debentures	$	75,000	$	332,500	$	650,000	$	—	$	450,000




Total	$	75,000	$	332,500	$	650,000	$	—	$	450,000

Short-Term Debt

In June 2025, Southwest Gas Holdings entered into a new $300.0 million revolving credit agreement that matures in August 2029 and replaced Southwest Gas Holdings’ existing $300.0 million credit facility that was set to expire in December 2026. At December 31, 2025, the applicable margin is 1.125% for loans bearing interest with reference to SOFR and 0.125% for loans bearing interest with reference to the alternative base rate. Southwest Gas Holdings has a one-week interest period option with an interest rate equal to Daily Simple SOFR plus 0.03839% plus the applicable margin. Southwest Gas Holdings is also required to pay a commitment fee on the unfunded portion of the commitments which ranges from 0.075% to 0.200%. The revolving credit agreement also contains a swingline loan sub-facility in an aggregate principal amount at any time outstanding not to exceed $30.0 million. At December 31, 2025, there were no borrowing outstanding under this credit facility.

Southwest Gas Holdings has a $550.0 million term loan that had been set to mature in June 2026. Prior to the execution of the amendment, Southwest Holdings prepaid a portion of the indebtedness, decreasing the balance from $550.0 million to $225.0 million, utilizing proceeds received from the Centuri separation transactions. In August 2025, Southwest Gas Holdings paid the remaining balance of $225.0 million utilizing proceeds received from additional Centuri separation transactions. See Note 13 - Dispositions.

As indicated above in the Long-Term debt table, the 8% Series debenture for $75.0 million matures in August 2026.

The weighted average effective interest rate of all short-term borrowings is 9.23% at December 31, 2025. There were no short-term borrowings at December 31, 2024.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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Pension and Other Postretirement Benefits

Background and Organization	12 Months Ended
Background and Organization	Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Organization	Note 1 - Background and Organization Nature of Operations. This is a combined annual report of the Company and Southwest Gas. The combined notes to the consolidated financial statements apply to the Company and Southwest Gas unless otherwise described. Southwest Gas Holdings, a Delaware corporation, is a holding company owning all of the shares of common stock of Southwest Gas; until April 22, 2024, all of the shares of common stock of Centuri Holdings, Inc. (“Centuri”); and until February 14, 2023, all of the shares of common stock of MountainWest. The Company’s businesses were managed within three separate reportable segments until February 2023, our Natural Gas Distribution segment (Southwest Gas), our Utility Infrastructure Services segment (Centuri), and our Pipeline and Storage segment (MountainWest). After February 2023, the businesses were managed within two reportable segments, our Natural Gas Distribution segment (Southwest Gas) and our Utility Infrastructure Services segment (Centuri) until August 2025, After August 2025, our business is solely comprised of our Natural Gas Distribution segment (see Note 16 - Segment Information). Southwest Gas is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest Gas are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. While mechanisms exist in all states in which Southwest Gas operates which decouple authorized operating cost recovery and profitability from the volume of natural gas sold, thereby also incentivizing energy conservation, results for the Natural Gas Distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures. In December 2022, the Company announced that its Board unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest in an all-cash transaction to Williams for $1.5 billion in total enterprise value, subject to certain adjustments. The sale closed on February 14, 2023. Also as part of this simplification strategy, the Company previously communicated that it would pursue a separation of Centuri. In April 2024, the Company and Centuri announced the completion of the Centuri IPO. Following the Centuri IPO, the Company owned approximately 81% of Centuri. From May 2025 through September 2025, the Company completed a series of secondary public offerings and private placements of its holdings of Centuri common stock and, on September 5, 2025, completed a sale of its remaining shares. The Company’s sale of Centuri (which represents the entirety of the Company’s Utility Infrastructure Services segment) met the criteria to be presented as discontinued operations in accordance with U.S. GAAP. See Note 2 - Summary of Significant Accounting Policies and Note 13 - Dispositions. After completion of the offering, the Company no longer owns any shares of Centuri common stock and no longer has governance rights afforded to it under the Separation Agreement including the right to nominate any of Centuri’s directors and any remaining consent rights over certain of Centuri’s corporate actions.

Pension and Other Postretirement Benefits

12 Months Ended

Dec. 31, 2025

Retirement Benefits [Abstract]

Note 10 - Pension and Other Postretirement Benefits

Southwest Gas Corporation

Employees’ Investment Plan

An EIP is offered to eligible employees of Southwest Gas through deduction of a percentage of base compensation, subject to IRS limitations. The EIP provides for purchases of various mutual fund investments and Company common stock. For employees hired on or before December 31, 2021, one-half of amounts deferred are matched up to a maximum matching contribution of 3.5% of an employee’s annual compensation. Employees hired on or after January 1, 2022, are eligible for non-elective employer contributions of 3% plus a matching contribution (dollar-for-dollar) up to 7% of eligible compensation. Officers hired after January 1, 2022, are similarly eligible for non-elective and matching contributions. Contributions to the plan by Southwest Gas were $12.2 million, $9.9 million, and $8.3 million for 2025, 2024, and 2023, respectively.

Deferred Compensation Plan

A deferred compensation plan is offered to all officers of Southwest Gas, regardless of hire date, and a separate deferred compensation plan is offered to members of the Company’s Board. The plans provide the opportunity to defer up to 100% of annual cash compensation. One-half of amounts deferred by officers are matched up to a maximum matching contribution of 3.5% of an officer’s annual base salary. Upon retirement, payments of compensation deferred, plus interest, are made in equal monthly installments over 10, 15, or 20 years, as elected by the participant. Directors have an additional option to receive such payments over a five-year period. Deferred compensation earns interest at a rate determined each January. The interest rate equals 150% of Moody’s Seasoned Corporate Bond Rate Index.

Pension and Postretirement Plans

A noncontributory QRP with defined benefits covering substantially all Southwest Gas employees hired on or before December 31, 2021, is available, in addition to a separate unfunded SERP, which is limited to Southwest Gas’ officers. PBOP are provided to qualified retirees for limited benefits related to health care, dental, vision and life insurance, some of which were subject to earlier “sunset” dates. The defined benefit QRP, SERP, and PBOP are not available to Southwest Gas employees hired on or after January 1, 2022. As noted above, employees hired on or after that date, are eligible for enhanced contributions to the EIP.

The overfunded or underfunded positions of defined benefit postretirement plans, including pension plans, are recognized in the Consolidated Balance Sheets. Any actuarial gains and losses, prior service costs, and transition assets or obligations are recognized in AOCI under Stockholders’ equity, net of tax, until they are amortized as a component of net periodic benefit cost.

A regulatory asset has been established for the portion of the total amounts otherwise chargeable to AOCI that are expected to be recovered through rates in future periods. Changes in actuarial gains and losses and prior service costs pertaining to the regulatory asset will be recognized as an adjustment to the regulatory asset account as these amounts are amortized and recognized as components of net periodic pension costs each year.

The QRP invests the majority of its plan assets in common collective trusts, which include a well-diversified portfolio of domestic and international equity securities and fixed income securities and are managed by a professional investment manager appointed by Southwest Gas. The investment manager has full discretionary authority to direct the investment of plan assets held in trust within the specific guidelines prescribed by Southwest Gas through the plan’s investment policy statement. Southwest Gas previously implemented an LDI strategy for part of the portfolio; a form of investing designed to better match the movement in pension plan assets with the impact of interest rate changes and, indirectly, inflation assumption changes on the pension plan liability. The implementation of the LDI strategy was intended to be phased in over time by using a glide path. The glide path was designed to increase the allocation of the plan’s assets to fixed income securities, as the funded status of the plan increases, in order to more closely match the duration of the plan assets to that of the plan liability. During the third quarter of 2025, the asset mix was adapted in accordance with an updated policy statement an allocation of approximately 45% equity securities and 55% fixed income securities with an estimated target hedge ratio of 95%. Beginning in 2024, a treasury futures overlay was added as part of the LDI strategy intending to manage interest rate fluctuations with the goal of reducing funded ratio volatility; as of the end of 2025, the pension plan was approximately 102% funded. While the overlay is intended for these purposes, there is no guarantee that these intentions will be achieved. Pension plan assets are held in a Master Trust. The pension plan funding policy is in compliance with the federal government’s funding requirements.

Pension costs for these plans are affected by the amount and timing of cash contributions to the plans, the return on plan assets, discount rates, and by employee demographics, including age, compensation, and length of service. Changes made to the provisions of the plans may also impact current and future pension costs. Actuarial formulas are used in the determination of pension costs and are affected by actual plan experience and assumptions about future experience. Key actuarial assumptions include the expected return on plan assets, the discount rate used in determining the projected benefit obligation and pension costs, and the assumed rate of increase in employee compensation. Relatively small changes in these assumptions, particularly the discount rate, may significantly affect pension costs and plan obligations for the QRP. In determining the discount rate, management matches the plan’s projected cash flows to a spot-rate yield curve based on highly rated corporate bonds.

The asset return assumption (which impacts the following year’s expense) remained consistent with the prior year. The rates are presented in the table below:


	December 31,
	2025		2024


Asset return assumption	7.00	%	7.00	%

Future years’ expense level movements (up or down) may continue to be greatly influenced by long-term interest rates, asset returns, and funding levels; however, management implemented a treasury futures overlay to primarily be responsive to changing interest rates, and therefore, indirectly, discount rates that will apply to the pension, in attempting to preserve funded status.

The following table sets forth the QRP, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income.


	Year Ended December 31,
	2025									2024
(Thousands of dollars)	QRP			SERP			PBOP			QRP			SERP			PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$	1,175,245		$	43,183		$	62,064		$	1,241,177		$	45,031		$	66,009
Service cost	24,394			231			1,168			28,252			243			1,287
Interest cost	65,588			2,383			3,426			60,387			2,167			3,178

Actuarial loss (gain)	2,877			2,464			1,418			(87,575)			(725)			(2,691)
Benefits paid	(69,232)			(3,688)			(4,897)			(66,996)			(3,533)			(5,719)
Benefit obligation at end of year (PBO/PBO/APBO)	1,198,872			44,573			63,179			1,175,245			43,183			62,064
Change in plan assets:
Market value of plan assets at beginning of year	1,120,272			—			38,122			1,166,372			—			35,920
Actual return on plan assets	148,883			—			5,337			896			—			3,027
Employer contributions	25,000			3,688			—			20,000			3,533			2,514
Benefits paid	(69,232)			(3,688)			(1,335)			(66,996)			(3,533)			(3,339)
Market value of plan assets at end of year	1,224,923			—			42,124			1,120,272			—			38,122
Funded status at year end	$	26,051		$	(44,573)		$	(21,055)		$	(54,973)		$	(43,183)		$	(23,942)
Weighted-average assumptions (benefit obligation):
Discount rate	5.75		%	5.50		%	5.50		%	5.75		%	5.75		%	5.75		%
Weighted-average rate of compensation increase	3.50		%	3.50		%	N/A			3.50		%	3.50		%	N/A

Funding for the plans above during calendar year 2026 is expected to be approximately $23.5 million, of which $20.0 million pertains to the QRP. Management monitors plan assets and liabilities and may, at its discretion, increase plan funding levels above the minimum in order to achieve a desired funded status and avoid or minimize potential benefit restrictions.

The accumulated benefit obligation for the QRP and the SERP is presented below:


	December 31,
(Thousands of dollars)	2025		2024
QRP	$	1,091,081	$	1,084,462
SERP	42,382		40,753

Benefits expected to be paid for the QRP, SERP, and PBOP over the next 10 years are as follows:


(Millions of dollars)	2026		2027		2028		2029		2030		2031-2035
QRP	$	72.0	$	73.0	$	74.0	$	75.0	$	77.0	$	409.0
SERP	3.5		3.5		3.4		3.4		3.4		16.2
PBOP	5.0		5.1		5.1		5.1		5.2		25.8

No assurance can be made that actual funding and benefits paid will match these estimates.

For PBOP measurement purposes, the per capita cost of the covered health care benefits medical rate trend assumption is 5.0%, declining to 4.5%. Specific contributions are made for health care benefits of employees who retire after 1988, but Southwest Gas pays all covered health care costs for employees who retired prior to 1989. The medical trend rate assumption noted above applies to the benefit obligations of pre-1989 retirees only.

The service cost component of net periodic benefit costs included in the table below is part of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of that portion of overall net periodic benefit costs to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily Operations and maintenance expense, Net regulated operations plant, and Deferred charges and other assets for both the Company and Southwest Gas. The non-service cost components of net periodic benefit cost are reflected in Other income (deductions) on the Consolidated Statements of Income of each entity, based on accounting guidance for the presentation of such costs. Variability in total net periodic benefit cost between periods, especially with regard to the QRP, is subject to changes in underlying actuarial assumptions between periods, notably the discount rate.

Components of net periodic benefit cost:


	2025									2024									2023
(Thousands of dollars)	QRP			SERP			PBOP			QRP			SERP			PBOP			QRP			SERP			PBOP
Service cost	$	24,394		$	231		$	1,168		$	28,252		$	243		$	1,287		$	25,840		$	250		$	1,269
Interest cost	65,588			2,383			3,426			60,387			2,167			3,178			59,165			2,123			3,302
Expected return on plan assets	(90,328)			—			(2,495)			(87,812)			—			(2,259)			(84,062)			—			(2,424)
Amortization of prior service cost	—			—			175			—			—			175			—			—			175
Amortization of net actuarial loss	3,007			1,082			(313)			6,308			1,333			—			336			998			—
Net periodic benefit cost	$	2,661		$	3,696		$	1,961		$	7,135		$	3,743		$	2,381		$	1,279		$	3,371		$	2,322
Weighted-average assumptions (net benefit cost)
Discount rate	5.75		%	5.75		%	5.75		%	5.00		%	5.00		%	5.00		%	5.25		%	5.25		%	5.25		%
Expected return on plan assets	7.00		%	N/A			7.00		%	6.75		%	N/A			6.75		%	6.75		%	N/A			6.75		%
Weighted-average rate of compensation increase	3.50		%	3.50		%	N/A			3.50		%	3.50		%	N/A			3.25		%	3.25		%	N/A

Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income


	Year Ended December 31,
	2025								2024								2023
(Thousands of dollars)	QRP		SERP		PBOP		Total		QRP		SERP		PBOP		Total		QRP		SERP		PBOP		Total
Net actuarial loss (gain) (a)	$	(55,680)	$	2,463	$	(1,423)	$	(54,640)	$	(659)	$	(725)	$	(3,458)	$	(4,842)	$	455	$	3,995	$	(1,262)	$	3,188
Amortization of prior service cost (b)	—		—		(175)		(175)		—		—		(175)		(175)		—		—		(175)		(175)
Amortization of net actuarial loss (b)	(3,007)		(1,081)		313		(3,775)		(6,308)		(1,333)		—		(7,641)		(335)		(998)		—		(1,333)

Regulatory adjustment	52,232		—		1,285		53,517		6,200		—		3,633		9,833		(107)		—		1,437		1,330
Recognized in other comprehensive (income) loss	(6,455)		1,382		—		(5,073)		(767)		(2,058)		—		(2,825)		13		2,997		—		3,010
Net periodic benefit costs recognized in net income	2,661		3,696		1,961		8,318		7,135		3,743		2,381		13,259		1,279		3,371		2,322		6,972
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$	(3,794)	$	5,078	$	1,961	$	3,245	$	6,368	$	1,685	$	2,381	$	10,434	$	1,292	$	6,368	$	2,322	$	9,982

The following table sets forth, by level within the three-level fair value hierarchy, the fair values of the assets of the QRP and the PBOP as of December 31, 2025 and 2024. The SERP has no assets.


	December 31,
	2025						2024
(Thousands of dollars)	QRP		PBOP		Total		QRP		PBOP		Total
Assets at fair value:
Level 2 – Significant other observable inputs
Government fixed income (1)	$	6,974	$	6	$	6,980	$	5,048	$	4	$	5,052
Total Level 2 assets	6,974		6		6,980		5,048		4		5,052
Investments measured at NAV:
Mutual funds (2)	—		40,790		40,790		—		36,951		36,951
Pooled funds and mutual funds (3)	24,289		306		24,595		15,009		191		15,200
Commingled trust equity funds (4)
Global	220,661		189		220,850		237,333		211		237,544
International	99,508		85		99,593		105,977		94		106,071
U.S. equity securities	176,970		152		177,122		171,122		153		171,275
Emerging markets	61,510		54		61,564		55,327		49		55,376
Commingled trust fixed income funds (5)	632,863		542		633,405		528,238		469		528,707
Insurance company general account contracts (6)	2,148		—		2,148		2,218		—		2,218
Total Plan assets	$	1,224,923	$	42,124	$	1,267,047	$	1,120,272	$	38,122	$	1,158,394

(3) These funds are collective short-term funds that invest in Treasury bills and money market funds and are used as a temporary cash repository.

▪Global equities, including domestic (U.S.) and international equities

▪International developed countries equities

▪Domestic (U.S.) equities

▪Emerging markets equities

The entire disclosure for retirement benefits.

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Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) officer $ / shares	Dec. 31, 2024 USD ($) officer $ / shares	Dec. 31, 2023 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of officers received special performance stock unit \| officer	1	3
Compensation expense \| $	$ 14,631	$ 11,372	$ 6,228
Compensation cost related to nonvested shares not yet recognized \| $	$ 7,300
Compensation cost not yet recognized, period for recognition	1 year 7 months 6 days
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in USD per share) \| $ / shares	$ 76.87	$ 68.54	$ 62.78
Restricted Stock Units/Director Deferred Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in USD per share) \| $ / shares	$ 75.42
Restricted Stock Units/Director Deferred Stock Units \| Vesting Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	40.00%
Restricted Stock Units/Director Deferred Stock Units \| Vesting Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	30.00%
Restricted Stock Units/Director Deferred Stock Units \| Vesting Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	30.00%
Restricted Stock/Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in USD per share) \| $ / shares		$ 62.55	$ 62.83
Omnibus Incentive Plan \| Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance measurement period	3 years
Compensation expense \| $	$ 6,200	$ 5,200	$ 1,100

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating revenues:
Regulated operations revenues	$ 1,940,380	$ 2,475,216	$ 2,534,696
Total operating revenues	1,940,380	2,475,216	2,534,696
Operating expenses:
Net cost of gas sold	497,636	1,150,005	1,253,269
Operations and maintenance	544,064	526,679	533,009
Depreciation and amortization	330,724	303,095	295,462
Taxes other than income taxes	94,070	88,965	88,751
Goodwill impairment and loss on sale	0	0	71,230
Total operating expenses	1,466,494	2,068,744	2,241,721
Operating income	473,886	406,472	292,975
Other income and (expenses):
Net interest deductions	(203,081)	(206,528)	(194,810)
Other income (deductions)	60,068	54,192	71,239
Total other income and (expenses)	(143,013)	(152,336)	(123,571)
Income from continuing operations before income taxes	330,873	254,136	169,404
Income tax expense	96,037	33,157	29,410
Income from continuing operations	234,836	220,979	139,994
Income (loss) from discontinued operations, net of income tax	200,344	(16,143)	15,523
Net income	435,180	204,836	155,517
Net income (loss) attributable to noncontrolling interests	(4,646)	6,021	4,628
Net income	$ 439,826	$ 198,815	$ 150,889
Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.:
Continuing operations (in USD per share)	$ 3.25	$ 3.08	$ 1.98
Discontinued operations (in USD per share)	2.84	(0.31)	0.15
Net earnings per share - basic (in USD per share)	6.09	2.77	2.13
Diluted earnings (loss) per share:
Continuing operations (in USD per share)	3.25	3.07	1.98
Discontinued operations (in USD per share)	2.83	(0.31)	0.15
Net earnings per share - diluted (in USD per share)	$ 6.08	$ 2.76	$ 2.13
Weighted average shares:
Basic (in shares)	72,162	71,841	70,787
Diluted (in shares)	72,337	72,032	70,990

Debt - Schedule of Effective Interest Rates on Variable-Rate IDRBs (Details)	Dec. 31, 2025	Dec. 31, 2024
2003 Series A, due 2038
Debt Instrument [Line Items]
Effective interest rates	3.50%	4.86%
2008 Series A, due 2038
Debt Instrument [Line Items]
Effective interest rates	3.84%	4.89%
2009 Series A, due 2039
Debt Instrument [Line Items]
Effective interest rates	3.75%	4.73%
Tax-exempt Series A, due 2028
Debt Instrument [Line Items]
Effective interest rates	3.10%	4.29%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Pension and Other Postretirement Benefits - Schedule of Net Periodic Benefit Cost and Weighted-Average Assumptions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 8,318	$ 13,259	$ 6,972
QRP
Defined Benefit Plan Disclosure [Line Items]
Service cost	24,394	28,252	25,840
Interest cost	65,588	60,387	59,165
Expected return on plan assets	(90,328)	(87,812)	(84,062)
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	3,007	6,308	336
Net periodic benefit cost	$ 2,661	$ 7,135	$ 1,279
Weighted-average assumptions (net benefit cost)
Discount rate	5.75%	5.00%	5.25%
Expected return on plan assets	7.00%	6.75%	6.75%
Weighted-average rate of compensation increase	3.50%	3.50%	3.25%
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 231	$ 243	$ 250
Interest cost	2,383	2,167	2,123
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	1,082	1,333	998
Net periodic benefit cost	$ 3,696	$ 3,743	$ 3,371
Weighted-average assumptions (net benefit cost)
Discount rate	5.75%	5.00%	5.25%
Weighted-average rate of compensation increase	3.50%	3.50%	3.25%
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,168	$ 1,287	$ 1,269
Interest cost	3,426	3,178	3,302
Expected return on plan assets	(2,495)	(2,259)	(2,424)
Amortization of prior service cost	175	175	175
Amortization of net actuarial loss	(313)	0	0
Net periodic benefit cost	$ 1,961	$ 2,381	$ 2,322
Weighted-average assumptions (net benefit cost)
Discount rate	5.75%	5.00%	5.25%
Expected return on plan assets	7.00%	6.75%	6.75%

Segment Information

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Information

Note 16 - Segment Information

The Company’s businesses were managed within the Natural Gas Distribution segment (Southwest Gas), the Utility Infrastructure Services segment (Centuri), and the Pipeline and Storage segment (MountainWest) through February 2023. The Company disposed of its Pipeline and Storage segment (MountainWest) in February 2023 and disposed of its Utility Infrastructure Services segment (Centuri) in August 2025 see Note 13 - Dispositions. The Company and Southwest Gas consist of a single reportable segment (Natural Gas Distribution) for all periods presented in these financial statements.

The Utility Infrastructure Services segment is presented as discontinued operations in the Consolidated Statements of Income and, as such, have been excluded from continuing operations and segment results. Previously reported results for the Natural Gas Distribution segment was not impacted by the Centuri deconsolidation or the revisions discussed in Note 3 - Revision of Previously Issued Financial Statements.

The Pipeline and Storage segment (MountainWest) was primarily engaged in the business of providing interstate transportation and underground storage services. The MountainWest sale did not meet the criteria for reporting discontinued operations as the sale did not represent a strategic shift that would have a major effect on the Company’s operations or financial results. Previously reported results for the Pipeline and Storage segment was not impacted by the Centuri deconsolidation or the revisions discussed in Note 3 - Revision of Previously Issued Financial Statements.

The Company’s CEO and Southwest Gas’ CEO and President have been identified as the CODM. The CODM reviews the Company’s income (loss) from continuing operations and Southwest Gas’ net income as reported on their respective consolidated statements of income in assessing performance and allocating resources. The CODM considers budget-to-actual variances against these metrics when making decisions about allocating capital and personnel. The CODM also uses income (loss) from continuing operations and net income to assess the return on assets, margin earned, and in assessing the compensation of certain employees.

Because both the Company and Southwest Gas operate as a single reportable segment, the related disclosure information is presented in the applicable sections. The other significant amounts required for disclosure are included within income (loss) from continuing operations and net income. Revenues from external customers are reported as “Revenues from contracts with customers” in Note 6 - Revenue for the years ended December 31, 2025, and December 31, 2024, and capital expenditures are reported as “Capital expenditures and property additions” in the consolidated statements of cash flows for the years ended December 31, 2025 and December 31, 2024. The measures of assets for the Company and Southwest Gas are reported as “Total assets” on their respective consolidated balance sheets. Refer to these statements for the results of the Natural Gas Distribution segment for the years ended December 31, 2025, December 31, 2024 and December 31, 2023.

As discussed above, the Utility Infrastructure Services segment was reclassified into discontinued operations and the Company only had multiple segments in calendar year 2023. The financial information pertaining to the Natural Gas Distribution and Pipeline and Storage segments as of and for the year ended December 31, 2023 is presented in the tables below. The accounting policies of the segments are the same as those described in Note 2 - Summary of Significant Accounting Policies. In order to reconcile to net income as disclosed in the Consolidated Statements of Income, an Other column is included below associated with certain expenses that represent the corporate and administrative activities associated with Southwest Gas Holdings, such as Operations and maintenance expenses and net interest deduction.


	Year Ended December 31, 2023
(Thousands of dollars)	Natural Gas Distribution		Pipeline and Storage (1)		Other		Total
Revenues from external customers	$	2,536,079	$	35,132	$	—	$	2,571,211
Alternative revenue program and other revenues	(36,515)		—		—		(36,515)
Total segment revenues	2,499,564		35,132		—		2,534,696
Less:
Net cost of gas sold	1,246,901		6,368		—		1,253,269
Operations and maintenance expense	511,646		11,378		9,985		533,009
Other segment items (2)	461,892		24,419		92,703		579,014
Income (loss) before income taxes	279,125		(7,033)		(102,688)		169,404
Income tax expense (benefit)	36,899		9,255		(16,744)		29,410
Income (loss) from continuing operations	242,226		(16,288)		(85,944)		139,994
Income from discontinued operations, net of taxes							15,523
Net income							155,517
Net income attributable to noncontrolling interests							4,628
Net income attributable to Southwest Gas Holdings, Inc.							$	150,889

(2) Other segment items for each reportable segment includes:

•Natural Gas Distribution: Depreciation and amortization, Taxes other than income taxes, Net interest deductions, and Other income (deductions).

•Pipeline and Storage: Depreciation and amortization, Taxes other than income taxes, Goodwill impairment and loss on sale, Net interest deductions, and Other income (deductions).


Other segment disclosures	Year Ended December 31, 2023
(Thousands of dollars)	Natural Gas Distribution		Pipeline and Storage (1)		Other		Total
Interest income	$	50,757	$	—	$	—	$	50,757
Interest expense	$	149,830	$	2,200	$	42,780	$	194,810
Depreciation and amortization	$	295,462	$	—	$	—	$	295,462
Goodwill impairment and loss on sale	$	—	$	21,215	$	50,015	$	71,230
Segment assets	$	9,268,571	$	—	$	8,735	$	9,277,306
Capital expenditures	$	762,081	$	3,790	$	—	$	765,871

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/280/tableOfContent

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

Receivables and Related Allowances - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Receivables [Abstract]
Gas utility customer accounts receivable balance	$ 163,752	$ 194,177

Revision of Previously Issued Financial Statements - Schedule of Effects of the Prior-Period Errors on the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
ASSETS
Accounts receivable, net of allowances	$ 170,601				$ 203,012
Total current assets	1,192,092				1,464,345
Total assets	10,429,477				12,072,906	$ 9,277,306
CAPITALIZATION AND LIABILITIES
Retained earnings	1,022,846	$ 964,286	$ 742,452		758,649
Total equity	3,961,119	3,893,566	3,647,386		3,504,187
Total capitalization	7,394,131	7,325,686	8,493,100		7,193,559
Accounts payable	225,732				190,918
Deferred purchased gas costs	310,085				255,398
Total current liabilities	929,898	879,703			1,831,967
Deferred income taxes and investment tax credits, net	977,312	940,717	954,757		857,982
Total deferred income taxes and other credits	2,105,448	2,123,190	2,306,340		3,047,380
Total capitalization and liabilities	10,429,477	10,328,579	12,213,945		12,072,906
Southwest Gas Corporation
ASSETS
Accounts receivable, net of allowances					200,847
Total current assets	768,129				856,955
Total assets	9,993,991				9,531,725
CAPITALIZATION AND LIABILITIES
Retained earnings	1,314,911	1,209,265	1,203,006	$ 1,202,052	1,059,773
Total equity	3,524,966	3,392,532	3,383,619	3,380,149	3,235,486
Total capitalization	6,957,978	6,824,652	6,889,856	6,885,501	6,739,963
Accounts payable					192,609
Deferred purchased gas costs	310,085				253,401
Total current liabilities	884,724	826,278			769,026
Deferred income taxes and investment tax credits, net	1,027,921	896,275	896,401	894,709	854,249
Total deferred income taxes and other credits	2,151,289	2,074,547	2,072,480	2,061,958	2,022,736
Total capitalization and liabilities	$ 9,993,991	9,725,477	9,688,433	9,679,467	9,531,725
As Reported
CAPITALIZATION AND LIABILITIES
Retained earnings		999,399	769,723
Total equity		3,928,679	3,674,657
Total capitalization		7,435,799	8,520,371
Total current liabilities		804,703			769,026
Deferred income taxes and investment tax credits, net		905,604	927,486
Total deferred income taxes and other credits		2,088,077	2,279,069
Total capitalization and liabilities		10,328,579	12,213,945
As Reported \| Southwest Gas Corporation
ASSETS
Accounts receivable, net of allowances					202,947
Total current assets					859,055
Total assets					9,533,825
CAPITALIZATION AND LIABILITIES
Retained earnings		1,233,196	1,227,760	1,238,775	1,096,149
Total equity		3,416,463	3,408,373	3,416,872	3,271,862
Total capitalization		6,923,583	6,914,610	6,922,224	6,776,339
Accounts payable					190,612
Deferred purchased gas costs					255,398
Total current liabilities		751,278
Deferred income taxes and investment tax credits, net		872,344	871,647	857,986	819,973
Total deferred income taxes and other credits		2,050,616	2,047,726	2,025,235	1,988,460
Total capitalization and liabilities		9,725,477	9,688,433	9,679,467	9,533,825
Adjustments
CAPITALIZATION AND LIABILITIES
Retained earnings		(35,113)	(27,271)
Total equity		(35,113)	(27,271)
Total capitalization		(110,113)	(27,271)
Total current liabilities		75,000			0
Deferred income taxes and investment tax credits, net		35,113	27,271
Total deferred income taxes and other credits		35,113	27,271
Total capitalization and liabilities		0	0
Adjustments \| Southwest Gas Corporation
ASSETS
Accounts receivable, net of allowances					(2,100)
Total current assets					(2,100)
Total assets					(2,100)
CAPITALIZATION AND LIABILITIES
Retained earnings		(23,931)	(24,754)	(36,723)	(36,376)
Total equity		(23,931)	(24,754)	(36,723)	(36,376)
Total capitalization		(98,931)	(24,754)	(36,723)	(36,376)
Accounts payable					1,997
Deferred purchased gas costs					(1,997)
Total current liabilities		75,000
Deferred income taxes and investment tax credits, net		23,931	24,754	36,723	34,276
Total deferred income taxes and other credits		23,931	24,754	36,723	34,276
Total capitalization and liabilities		$ 0	$ 0	$ 0	$ (2,100)

Previously Issued Condensed Consolidated Financial Statements (Unaudited) - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ 260,117	$ (37,600)		$ 71,587	$ 331,704	$ 435,180	$ 204,836	$ 155,517
Income (loss) from continuing operations, net of income tax	(3,667)				129,890	234,836	220,979	139,994
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				121,304	83,254	118,112	57,730	59,392
Changes in current assets and liabilities:
Accounts receivable, net of allowances						32,411	66,275	(38,387)
Deferred purchased gas costs						63,280	706,896	177,177
Accounts payable						13,172	(20,006)	(256,399)
Net cash provided by operating activities of continuing operations					509,136	594,161	1,205,332	350,505
Net cash provided by operating activities				417,611	474,508	556,076	1,355,780	509,211
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	6,343	45,646	$ 142,595	188,241	194,584	300,308	262,096	228,412
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			40,375	41,982	42,545	172,454	68,954	71,874
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(13,217)	66,211	90,272		68,348
Deferred purchased gas costs			55,862	122,706	116,765	65,277	714,958	188,226
Accounts payable			(46,688)	(71,229)	(68,234)	11,086	(19,735)	(253,239)
Net cash provided by operating activities			285,832	459,287	526,359	$ 618,815	1,252,982	391,545
As Reported
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	267,959	(10,329)		98,858	366,817
Income (loss) from continuing operations, net of income tax	4,175				165,003
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				94,033	48,141
Changes in current assets and liabilities:
Net cash provided by operating activities of continuing operations					509,136
Net cash provided by operating activities				417,611	474,508
As Reported \| Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	5,520	33,677	142,942	176,619	182,139		261,176	242,226
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			37,928	51,504	52,890		69,459	66,611
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(11,117)	68,311	92,372		66,248
Deferred purchased gas costs			53,865	120,709	114,768		706,896	192,182
Accounts payable			(44,691)	(69,232)	(66,237)		(19,032)	(260,403)
Net cash provided by operating activities			285,832	459,287	526,359		1,252,982	391,545
Adjustments
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	(7,842)	(27,271)		(27,271)	(35,113)
Income (loss) from continuing operations, net of income tax	(7,842)				(35,113)
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes				27,271	35,113
Changes in current assets and liabilities:
Deferred purchased gas costs							(74,300)	(294,900)
Net cash provided by operating activities of continuing operations					0
Net cash provided by operating activities				0	0
Adjustments \| Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ 823	$ 11,969	(347)	11,622	12,445		920	(13,814)
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes			2,447	(9,522)	(10,345)		(505)	5,263
Changes in current assets and liabilities:
Accounts receivable, net of allowances			(2,100)	(2,100)	(2,100)		2,100
Deferred purchased gas costs			1,997	1,997	1,997		8,062	(3,956)
Accounts payable			(1,997)	(1,997)	(1,997)		(703)	7,164
Net cash provided by operating activities			$ 0	$ 0	$ 0		$ 0	$ 0

Revenue - Narrative (Details) $ in Millions	12 Months Ended
Revenue - Narrative (Details) $ in Millions	Dec. 31, 2025 USD ($) type customer
Segment Reporting Information [Line Items]
Number of customers party to contracts with rate components subject to negotiation (less than) \| customer	24
Revenue, backlog performance obligations	$ 58.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Segment Reporting Information [Line Items]
Revenue, backlog performance obligations	$ 15.9
Revenue, backlog performance obligations, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Segment Reporting Information [Line Items]
Revenue, backlog performance obligations	$ 15.9
Revenue, backlog performance obligations, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Segment Reporting Information [Line Items]
Revenue, backlog performance obligations	$ 15.9
Revenue, backlog performance obligations, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01
Segment Reporting Information [Line Items]
Revenue, backlog performance obligations	$ 10.5
Revenue, backlog performance obligations, period	1 year
Southwest Gas Corporation
Segment Reporting Information [Line Items]
Number of types of services provided to customers \| type	2
Number of customers \| customer	2,300,000

Pension and Other Postretirement Benefits - Schedule of Fair Value of Plan Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) day	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 1,267,047	$ 1,158,394
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, shares redeemed with notice, period \| day	1
Equity Securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	25.00%
Equity Securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	75.00%
Fixed Income Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	25.00%
Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	30.00%
Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 6,980	5,052
Level 2 – Significant other observable inputs \| Government fixed income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,980	5,052
Investments measured at NAV: \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	40,790	36,951
Investments measured at NAV: \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	24,595	15,200
Investments measured at NAV: \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	220,850	237,544
Investments measured at NAV: \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	99,593	106,071
Investments measured at NAV: \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	177,122	171,275
Investments measured at NAV: \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	61,564	55,376
Investments measured at NAV: \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	633,405	528,707
Investments measured at NAV: \| Insurance Company General Account Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	2,148	2,218
QRP
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,224,923	1,120,272	$ 1,166,372
QRP \| Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,974	5,048
QRP \| Level 2 – Significant other observable inputs \| Government fixed income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,974	5,048
QRP \| Investments measured at NAV: \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
QRP \| Investments measured at NAV: \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	24,289	15,009
QRP \| Investments measured at NAV: \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	220,661	237,333
QRP \| Investments measured at NAV: \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	99,508	105,977
QRP \| Investments measured at NAV: \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	176,970	171,122
QRP \| Investments measured at NAV: \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	61,510	55,327
QRP \| Investments measured at NAV: \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	632,863	528,238
QRP \| Investments measured at NAV: \| Insurance Company General Account Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	2,148	2,218
PBOP
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	42,124	38,122	$ 35,920
PBOP \| Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6	4
PBOP \| Level 2 – Significant other observable inputs \| Government fixed income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6	4
PBOP \| Investments measured at NAV: \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	40,790	36,951
PBOP \| Investments measured at NAV: \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	306	191
PBOP \| Investments measured at NAV: \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	189	211
PBOP \| Investments measured at NAV: \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	85	94
PBOP \| Investments measured at NAV: \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	152	153
PBOP \| Investments measured at NAV: \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	54	49
PBOP \| Investments measured at NAV: \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	542	469
PBOP \| Investments measured at NAV: \| Insurance Company General Account Contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 0	$ 0

Dispositions - Schedule of Net Gain from Discontinued Operation (Details) - Centuri Holdings, Inc. - Discontinued Operations, Disposed of by Sale - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Aug. 11, 2025	Aug. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Fair value of the retained investment in Centuri	$ 533,636
Net proceeds received from the August 11, 2025 public offering and private placement	355,220
Carrying value of noncontrolling interest attributable to Centuri prior to deconsolidation	460,897
Centuri deferred tax asset adjustment	(24,257)
Less: Carrying value of Centuri net assets prior to deconsolidation, including AOCI	(982,396)
Gain on deconsolidation of Centuri before income tax	343,100		$ 343,100	$ 0	$ 0
Income tax expense	82,650	$ 82,700
Gain on deconsolidation of Centuri, net of tax	$ 260,450
Discontinued Operation, Gain (Loss) On Disposal Statement Of Income Or Comprehensive Income, Extensible Enumeration Not Disclosed Flag	Gain on deconsolidation of Centuri, net of tax
Gain on interest sold	$ 120,200
Gain on the investment retained	$ 222,900

Dispositions - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended					3 Months Ended		10 Months Ended	12 Months Ended
	Sep. 05, 2025	Aug. 11, 2025	Jul. 08, 2025	Jun. 18, 2025	May 22, 2025	Sep. 05, 2025	Aug. 31, 2025	Jul. 31, 2025	Jun. 30, 2025	May 31, 2025	Dec. 31, 2025	Sep. 05, 2025	Dec. 31, 2025	Dec. 31, 2025	Aug. 01, 2025	Dec. 31, 2024	Apr. 30, 2024	Feb. 14, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense related to outside basis of investment														$ 52,800
Income tax benefit related to deferred tax assets														24,100
Tax assets agreement, capital contribution											$ 24,300		$ 80,700
Redeemable noncontrolling interest											$ 0		$ 0	$ 0		$ 7,660
Centuri Holdings, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage		30.90%
Realized gain (loss) on disposal of equity method investment	$ (9,700)	$ 222,900				$ 213,200
Centuri Holdings, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage by parent															52.10%		81.00%
Public Offering, Including Over-Allotment Option
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)									11,212,500	10,350,000
Sale of stock, price per share (in USD per share)									$ 20.75	$ 17.50
Stock issuance costs									$ 8,600	$ 6,600
Net proceeds from sale of stock									$ 224,100	$ 224,600
Over-Allotment Option
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)									1,462,500	1,350,000
Private Placement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sale of stock			$ 22,000
Private Placement \| Ichan Partners LP & Ichan Partners Master Fund LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)								1,060,240		2,857,142
Net proceeds from sale of stock								$ 22,000
Public Offering And Private Placement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)		18,823,500			13,207,142
Sale of stock, price per share (in USD per share)		$ 19.50
Stock issuance costs		$ 11,800
Net proceeds from sale of stock		355,200			$ 224,600							$ 1,349,900
Public Offering
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares (in shares)	27,362,210
Sale of stock, price per share (in USD per share)	$ 19.18					$ 19.18						$ 19.18
Stock issuance costs	$ 900
Net proceeds from sale of stock	$ 524,000			$ 224,100
Disposal Group, Held-for-sale, Not Discontinued Operations \| MountainWest
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage disposed																			100.00%
Discontinued operation, consideration																			$ 1,500,000
Discontinued Operations, Disposed of by Sale \| MountainWest
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage disposed																		100.00%
Discontinued operation, consideration																		$ 1,500,000
Discontinued Operations, Disposed of by Sale \| Centuri Holdings, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sale of stock		355,220
Income tax expense		$ 82,650					$ 82,700
Income tax benefit related to final disposition, release of valuation allowance and other separation costs							5,600
Income tax benefit resulting from operations through deconsolidation							2,000
Income tax expense from deconsolidation							$ 103,700

Previously Issued Condensed Consolidated Financial Statements (Unaudited) - Schedule of Effects of the Prior-Period Errors on the Consolidated Statements of Equity (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 4,088,534		$ 3,681,422	$ 3,681,422	$ 3,310,036	$ 3,058,759
Net income (loss)	262,634	$ (40,154)		439,826	198,815	150,889
Ending balance	3,893,566	4,088,534		3,961,119	3,681,422	3,310,036
Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,383,619	3,380,149	3,235,486	3,235,486	3,146,319	2,545,693
Net income (loss)	6,343	45,646	142,595	300,308	262,096	228,412
Ending balance	3,392,532	3,383,619	3,380,149	3,524,966	3,235,486	3,146,319
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	742,452		758,649	758,649	738,839	747,069
Net income (loss)				439,826	198,815	150,889
Ending balance	964,286	742,452		1,022,846	758,649	738,839
Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,203,006	1,202,052	1,059,773	1,059,773	981,178	911,873
Net income (loss)				300,308	262,096	228,412
Ending balance	1,209,265	1,203,006	1,202,052	1,314,911	1,059,773	981,178
Southwest Gas Holdings, Inc.
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,647,386		3,504,187	3,504,187	3,310,036	3,058,759
Net income (loss)				439,826	198,815	150,889
Ending balance	3,893,566	3,647,386		3,961,119	3,504,187	3,310,036
As Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	4,115,805
Net income (loss)	270,476	(12,883)
Ending balance	3,928,679	4,115,805
As Reported \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,408,373	3,416,872	3,271,862	3,271,862	3,183,615	2,569,175
Net income (loss)	5,520	33,677	142,942		261,176	242,226
Ending balance	3,416,463	3,408,373	3,416,872		3,271,862	3,183,615
As Reported \| Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	769,723
Ending balance	999,399	769,723
As Reported \| Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,227,760	1,238,775	1,096,149	1,096,149	1,018,474	935,355
Ending balance	1,233,196	1,227,760	1,238,775		1,096,149	1,018,474
As Reported \| Southwest Gas Holdings, Inc.
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	3,674,657
Ending balance	3,928,679	3,674,657
Adjustments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(27,271)
Net income (loss)	(7,842)	(27,271)
Ending balance	(35,113)	(27,271)
Adjustments \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(24,754)	(36,723)	(36,376)	(36,376)	(37,296)	(23,482)
Net income (loss)	823	11,969	(347)		920	(13,814)
Ending balance	(23,931)	(24,754)	(36,723)		(36,376)	(37,296)
Adjustments \| Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(27,271)
Ending balance	(35,113)	(27,271)
Adjustments \| Retained Earnings \| Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(24,754)	(36,723)	(36,376)	$ (36,376)	(37,296)	(23,482)
Ending balance	(23,931)	(24,754)	$ (36,723)		$ (36,376)	$ (37,296)
Adjustments \| Southwest Gas Holdings, Inc.
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(27,271)
Ending balance	$ (35,113)	$ (27,271)

Amount of equity (deficit) attributable to parent and noncontrolling interest. Excludes temporary equity.

Regulated Operations Plant

12 Months Ended

Dec. 31, 2025