v3.26.1
Previously Issued Condensed Consolidated Financial Statements - Schedule of Effects of the Prior-Period Errors on the Condensed Consolidated Statements of Cash Flows (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss) $ 42,122 $ (37,600) $ 180,496 $ 71,587
Less: Loss from discontinued operations, net of income tax 0 (36,869) 0 (61,970)
Income (loss) from continuing operations, net of income tax 42,122 (731) 180,496 133,557
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization 77,846 68,940 177,449 162,630
Deferred income taxes     62,219 76,117
Gains on sale of property and equipment     0 (1,604)
Share-based compensation expense     6,880 7,253
Changes in current assets and liabilities:        
Accounts receivable, net of allowances     52,022 68,319
Deferred purchased gas costs     (18,056) 120,709
Accounts payable     (84,060) (68,915)
Accrued taxes     (2,319) (21,136)
Other current assets and liabilities     (87,009) (44,512)
Changes in deferred charges and other assets     (1,360) (25,820)
Changes in other liabilities and deferred credits     (23,356) (21,193)
Net cash provided by operating activities of continuing operations     308,224 428,594
Net cash used in operating activities of discontinued operations     0 (10,983)
Net cash provided by operating activities     308,224 417,611
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions (320,400) (199,300) (529,116) (362,457)
Other     (333) (176)
Net cash used in investing activities of continuing operations     (521,577) (353,374)
Net cash used in investing activities of discontinued operations     0 (42,641)
Net cash used in investing activities     (521,577) (396,015)
CASH FLOW FROM FINANCING ACTIVITIES:        
Issuance of long-term debt, net       0
Retirement of long-term debt       0
Withholding remittance - share-based compensation     (5,303) (2,612)
Proceeds from the sale of Centuri stock, net       0
Other, including principal payments on finance leases     (175) (4,121)
Net cash used in financing activities of continuing operations     (92,774) (511,357)
Net cash provided by financing activities of discontinued operations     0 481,349
Net cash used in financing activities     (92,774) (30,008)
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized     87,500 137,866
Income taxes paid, net     507 13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities     (26,000) (5,783)
Continuing Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized     87,500 105,303
Income taxes paid, net     507 0
Decrease of capital expenditures in Accounts payable or Other current liabilities     (26,000) (4,000)
Discontinued Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized     0 32,563
Income taxes paid, net     0 13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities     0 (1,783)
Southwest Gas Corporation        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss) 40,757 45,646 178,528 188,241
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization $ 77,685 68,940 177,288 162,630
Deferred income taxes     56,785 41,982
Gains on sale of property and equipment     0 (1,604)
Share-based compensation expense     6,092 6,578
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       66,211
Deferred purchased gas costs     (18,056) 122,706
Accounts payable     (83,842) (71,229)
Accrued taxes     (2,319) (9,056)
Other current assets and liabilities     (83,780) (44,524)
Changes in deferred charges and other assets     (519) (26,378)
Changes in other liabilities and deferred credits     (23,895) (19,459)
Net cash provided by operating activities     409,095 459,287
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions     (529,116) (362,457)
Other     69 290
Net cash used in investing activities     (521,175) (352,908)
CASH FLOW FROM FINANCING ACTIVITIES:        
Withholding remittance - share-based compensation     (5,312) (2,613)
Other, including principal payments on finance leases     (144) (2,593)
Net cash used in financing activities     114,544 (94,415)
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized     87,500 87,245
Income taxes paid, net     0 53
Decrease of capital expenditures in Accounts payable or Other current liabilities     $ (26,000) (4,000)
As Reported        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   (10,329)   98,858
Less: Loss from discontinued operations, net of income tax   0   0
Income (loss) from continuing operations, net of income tax   (10,329)   98,858
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization   103,163   231,076
Deferred income taxes       94,033
Gains on sale of property and equipment       (2,188)
Share-based compensation expense       11,003
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       17,082
Accounts payable       (67,223)
Accrued taxes       (25,778)
Other current assets and liabilities       (70,993)
Changes in deferred charges and other assets       (13,147)
Changes in other liabilities and deferred credits       (19,010)
Net cash provided by operating activities of continuing operations       417,611
Net cash used in operating activities of discontinued operations       0
Net cash provided by operating activities       417,611
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions       (407,619)
Other       2,345
Net cash used in investing activities of continuing operations       (396,015)
Net cash used in investing activities of discontinued operations       0
Net cash used in investing activities       (396,015)
CASH FLOW FROM FINANCING ACTIVITIES:        
Issuance of long-term debt, net       113,932
Retirement of long-term debt       (75,125)
Withholding remittance - share-based compensation       (3,544)
Proceeds from the sale of Centuri stock, net       448,662
Other, including principal payments on finance leases       (9,309)
Net cash used in financing activities of continuing operations       (30,008)
Net cash provided by financing activities of discontinued operations       0
Net cash used in financing activities       (30,008)
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       137,866
Income taxes paid, net       13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities       (5,783)
As Reported | Continuing Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       137,866
Income taxes paid, net       13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities       (5,783)
As Reported | Discontinued Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
As Reported | Southwest Gas Corporation        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   33,677   176,619
Adjustments to reconcile net income to net cash provided by operating activities:        
Deferred income taxes       51,504
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       68,311
Deferred purchased gas costs       120,709
Accounts payable       (69,232)
Net cash provided by operating activities       459,287
Adjustments        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   (27,271)   (27,271)
Less: Loss from discontinued operations, net of income tax   0   0
Income (loss) from continuing operations, net of income tax   (27,271)   (27,271)
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization   0   0
Deferred income taxes       27,271
Gains on sale of property and equipment       0
Share-based compensation expense       0
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       0
Accounts payable       0
Accrued taxes       0
Other current assets and liabilities       0
Changes in deferred charges and other assets       0
Changes in other liabilities and deferred credits       0
Net cash provided by operating activities of continuing operations       0
Net cash used in operating activities of discontinued operations       0
Net cash provided by operating activities       0
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions       0
Other       0
Net cash used in investing activities of continuing operations       0
Net cash used in investing activities of discontinued operations       0
Net cash used in investing activities       0
CASH FLOW FROM FINANCING ACTIVITIES:        
Issuance of long-term debt, net       0
Retirement of long-term debt       0
Withholding remittance - share-based compensation       0
Proceeds from the sale of Centuri stock, net       0
Other, including principal payments on finance leases       0
Net cash used in financing activities of continuing operations       0
Net cash provided by financing activities of discontinued operations       0
Net cash used in financing activities       0
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
Adjustments | Continuing Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
Adjustments | Discontinued Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
Adjustments | Southwest Gas Corporation        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   11,969   11,622
Adjustments to reconcile net income to net cash provided by operating activities:        
Deferred income taxes       (9,522)
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       (2,100)
Deferred purchased gas costs       1,997
Accounts payable       (1,997)
Net cash provided by operating activities       0
As Restated        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   (37,600)   71,587
Less: Loss from discontinued operations, net of income tax   0   0
Income (loss) from continuing operations, net of income tax   (37,600)   71,587
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization   103,163   231,076
Deferred income taxes       121,304
Gains on sale of property and equipment       (2,188)
Share-based compensation expense       11,003
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       17,082
Accounts payable       (67,223)
Accrued taxes       (25,778)
Other current assets and liabilities       (70,993)
Changes in deferred charges and other assets       (13,147)
Changes in other liabilities and deferred credits       (19,010)
Net cash provided by operating activities of continuing operations       417,611
Net cash used in operating activities of discontinued operations       0
Net cash provided by operating activities       417,611
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions       (407,619)
Other       2,345
Net cash used in investing activities of continuing operations       (396,015)
Net cash used in investing activities of discontinued operations       0
Net cash used in investing activities       (396,015)
CASH FLOW FROM FINANCING ACTIVITIES:        
Issuance of long-term debt, net       113,932
Retirement of long-term debt       (75,125)
Withholding remittance - share-based compensation       (3,544)
Proceeds from the sale of Centuri stock, net       448,662
Other, including principal payments on finance leases       (9,309)
Net cash used in financing activities of continuing operations       (30,008)
Net cash provided by financing activities of discontinued operations       0
Net cash used in financing activities       (30,008)
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       137,866
Income taxes paid, net       13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities       (5,783)
As Restated | Continuing Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       137,866
Income taxes paid, net       13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities       (5,783)
As Restated | Discontinued Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
Discontinued Operations        
CASH FLOW FROM OPERATING ACTIVITIES:        
Net income (loss)   0   0
Less: Loss from discontinued operations, net of income tax   (36,869)   (61,970)
Income (loss) from continuing operations, net of income tax   36,869   61,970
Adjustments to reconcile net income to net cash provided by operating activities:        
Depreciation and amortization   $ (34,223)   (68,446)
Deferred income taxes       (45,187)
Gains on sale of property and equipment       584
Share-based compensation expense       (3,750)
Changes in current assets and liabilities:        
Accounts receivable, net of allowances       51,237
Accounts payable       (1,692)
Accrued taxes       4,642
Other current assets and liabilities       26,481
Changes in deferred charges and other assets       (12,673)
Changes in other liabilities and deferred credits       (2,183)
Net cash provided by operating activities of continuing operations       10,983
Net cash used in operating activities of discontinued operations       (10,983)
Net cash provided by operating activities       0
CASH FLOW FROM INVESTING ACTIVITIES:        
Capital expenditures and property additions       45,162
Other       (2,521)
Net cash used in investing activities of continuing operations       42,641
Net cash used in investing activities of discontinued operations       (42,641)
Net cash used in investing activities       0
CASH FLOW FROM FINANCING ACTIVITIES:        
Issuance of long-term debt, net       (113,932)
Retirement of long-term debt       75,125
Withholding remittance - share-based compensation       932
Proceeds from the sale of Centuri stock, net       (448,662)
Other, including principal payments on finance leases       5,188
Net cash used in financing activities of continuing operations       (481,349)
Net cash provided by financing activities of discontinued operations       481,349
Net cash used in financing activities       0
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       0
Income taxes paid, net       0
Decrease of capital expenditures in Accounts payable or Other current liabilities       0
Discontinued Operations | Continuing Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       (32,563)
Income taxes paid, net       (13,069)
Decrease of capital expenditures in Accounts payable or Other current liabilities       1,783
Discontinued Operations | Discontinued Operations        
SUPPLEMENTAL INFORMATION:        
Interest paid, net of amounts capitalized       32,563
Income taxes paid, net       13,069
Decrease of capital expenditures in Accounts payable or Other current liabilities       $ (1,783)