Acquisitions and Dispositions (Sale of Kewaunee) (Narrative) (Detail) - Dominion Energy Kewaunee, Inc - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	May 31, 2021
Business Acquisition And Dispositions [Line Items]
Percentage of equity interests expected to be sold		100.00%
Disposal group, loss (gain) recorded	$ 649
Disposal group, loss (gain) recorded after tax	513
Withdrawal to recover nuclear fuel and other permitted costs	$ 80