Operating Segments (Schedule of Segment Reporting Information, by Segment, Virginia Power) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Operating Revenue		$ 3,038	$ 3,106	$ 6,908	$ 7,044
Net income (loss)		285	(1,169)	1,293	(1,439)
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue	[1]	1,741	1,805	3,571	3,735
Net income (loss)		414	490	788	210
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue		1,747	1,814	3,732	3,749
Dominion Energy Virginia | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		1,741	1,805	3,722	3,735
Net income (loss)		429	435	861	862
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue		120	242	220	593
Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue		0	0	(151)	0
Net income (loss)		$ (15)	$ 55	$ (73)	$ (652)

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