Operating Segments (Schedule of Segment Reporting Information, by Segment, Virginia Power) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Operating Revenue		$ 3,870	$ 3,938
Net income (loss)		1,008	(270)
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue	[1]	1,830	1,930
Net income (loss)		374	(280)
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue		1,985	1,935
Dominion Energy Virginia | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		1,981	1,930
Net income (loss)		432	427
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue		100	351
Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		(151)	0
Net income (loss)		$ (58)	$ (707)

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