v3.26.1
Previously Issued Condensed Consolidated Financial Statements - Schedule of Effects of the Prior-Period Errors on the Condensed Consolidated Statements of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss) $ 42,122 $ (37,600) $ 180,496 $ 71,587
Comprehensive income (loss) 66,291 (30,622) 205,111 78,937
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc. 66,291 (34,241) 205,111 79,981
Southwest Gas Corporation        
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss) 40,757 45,646 178,528 188,241
Comprehensive income (loss) $ 64,926 45,913 $ 203,143 188,776
As Reported        
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss)   (10,329)   98,858
Comprehensive income (loss)   (3,351)   106,208
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.   (6,970)   107,252
As Reported | Southwest Gas Corporation        
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss)   33,677   176,619
Comprehensive income (loss)   33,944   177,154
Adjustments        
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss)   (27,271)   (27,271)
Comprehensive income (loss)   (27,271)   (27,271)
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.   (27,271)   (27,271)
Adjustments | Southwest Gas Corporation        
Error Corrections and Prior Period Adjustments Restatement [Line Items]        
Net income (loss)   11,969   11,622
Comprehensive income (loss)   $ 11,969   $ 11,622