Electric Plant - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) unit facility mi MW	Dec. 31, 2020 USD ($)
Wildcat Point [Member]
Property, Plant and Equipment [Line Items]
Power facility output	980
North Anna [Member]
Property, Plant and Equipment [Line Items]
Power facility output	1,892
Undivided ownership interest	11.60%
Number of units | unit	2
Percentage of costs responsible for	11.60%
Outstanding accounts payable balance | $	$ 7.9	$ 3.8
Clover [Member]
Property, Plant and Equipment [Line Items]
Power facility output	877
Undivided ownership interest	50.00%
Number of units | unit	2
Outstanding accounts payable balance | $	$ 5.5	$ 2.1
Combustion Turbine Facilities [Member]
Property, Plant and Equipment [Line Items]
Number of combustion facilities | facility	2
Distributed Generation Facilities [Member]
Property, Plant and Equipment [Line Items]
Number of distributed facilities | facility	6
Other [Member]
Property, Plant and Equipment [Line Items]
Transmission lines | mi	110