Components of Gas Inventory (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 1.8	$ 1.0
Liquefied Natural Gas & Other
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	0.4	0.1
Natural Gas
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	1.0	0.5
Propane
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.4	$ 0.4