Operating Segments (Schedule of Segment Reporting Information, by Segment, Virginia Power) (Detail) - USD ($) $ in Millions			3 Months Ended								12 Months Ended
		Nov. 30, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenue			$ 3,521	$ 3,607	$ 3,106	$ 3,938	$ 3,895	$ 3,782	$ 3,443	$ 3,281	$ 14,172		$ 14,401		$ 11,199
Depreciation, depletion and amortization											2,332		2,283		1,660
Interest income											107		97		80
Interest and related charges											1,377		1,486		1,279
Income tax expense		$ 336									83		209		522
Net income (loss)			682	356	(1,169)	(270)	1,009	975	54	(680)	(401)		1,358		2,447
Capital expenditures											6,331		5,321		4,405
Total assets			95,905				103,823				95,905		103,823
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue											7,787		8,157		7,849
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue											1,163		832		629
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating Revenue			1,780	2,248	1,805	1,930	1,941	2,264	1,938	1,965	7,763	[1]	8,108	[1]	7,619	[1]
Depreciation, depletion and amortization											1,252		1,223		1,132
Interest income											11		11		10
Interest and related charges	[1]										516		524		511
Income tax expense											229		264		300
Net income (loss)			336	$ 475	$ 490	$ (280)	427	$ 602	$ 100	$ 20	1,021		1,149		1,282
Capital expenditures											3,372		2,981		2,542
Total assets			43,654				41,428				43,654		41,428
Virginia Electric and Power Company | Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue											7,763		8,137		7,835
Depreciation, depletion and amortization											1,245		1,215		1,157
Interest income											11		11		10
Interest and related charges											524		529		516
Income tax expense											500		481		378
Net income (loss)											1,884		1,783		1,594
Capital expenditures											3,372		2,981		2,542
Total assets			43,700				41,400				43,700		41,400
Virginia Electric and Power Company | Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue											0		(29)		(216)
Depreciation, depletion and amortization											7		8		(25)
Interest income											0		0		0
Interest and related charges											(8)		(5)		(5)
Income tax expense											(271)		(217)		(78)
Net income (loss)											(863)		(634)		(312)
Capital expenditures											0		0		$ 0
Total assets			$ 0				$ 0				$ 0		$ 0

[1] See Note 25 for amounts attributable to affiliates.