Related-Party Transactions (Detail) - Virginia Electric and Power Company - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Commodity purchases from affiliates		$ 1,423	$ 742	$ 569
Services provided by affiliates	[1]	519	494	455
Affiliated Entity
Related Party Transaction [Line Items]
Services provided to affiliates		$ 18	$ 18	$ 18

[1] Includes capitalized expenditures of $177 million, $161 million and $141 million for the years ended December 31, 2022, 2021 and 2020, respectively.