v3.26.1
Revenues - Schedule of Revenue Disaggregated by Service Type and Contract Type (Details) - Southwest Gas Corporation - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers $ 290,852 $ 368,861 $ 833,890 $ 1,125,618
Alternative revenue program revenues 65,285 24,870 105,430 12,504
Other revenues 2,017 2,587 3,953 4,612
Total Regulated operations revenues 358,154 396,318 943,273 1,142,734
Residential        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 189,417 238,844 587,721 800,483
Small commercial        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 55,319 72,024 144,026 202,389
Large commercial        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 13,247 17,921 28,399 39,636
Industrial/other        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 7,337 10,669 17,647 24,141
Transportation        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers $ 25,532 $ 29,403 $ 56,097 $ 58,969