v3.26.1
Components of Energy Supply Obligations (Detail) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current $ 10.6 $ 11.6 $ 11.1
Exchange Gas Obligation      
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current 8.7 9.3 8.7
Renewable Energy Portfolio Standards      
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current $ 1.9 $ 2.3 $ 2.4