v3.25.2
Components of Energy Supply Obligations (Detail) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Jun. 30, 2024
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current $ 11.1 $ 10.0 $ 8.6
Exchange Gas Obligation      
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current 8.7 6.0 5.5
Renewable Energy Portfolio Standards      
Contractual Obligation [Line Items]      
Energy Supply Obligations-Current $ 2.4 $ 4.0 $ 3.1