Operating Segments (Schedule of Segment Reporting Information, by Segment, Virginia Power) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Operating Revenue		$ 3,176	$ 3,607	$ 10,084	$ 10,651
Net income (loss)		654	356	1,947	(1,083)
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue	[1]	1,976	2,248	5,547	5,983
Net income (loss)		556	475	1,344	685
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue		2,330	2,254	6,062	6,003
Dominion Energy Virginia | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		2,326	2,248	6,048	5,983
Net income (loss)		601	615	1,462	1,477
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue		(391)	222	(171)	815
Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		(350)	0	(501)	0
Net income (loss)		$ (45)	$ (140)	$ (118)	$ (792)

[1] See Note 19 for amounts attributable to affiliates.