Accumulated Other Comprehensive Income (Loss) (Schedule of Changes in AOCI by Component Net of Tax) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]			$ 26,117
Total other comprehensive income (loss)		$ 31	$ 38	77		$ (187)
Ending balance		26,550		26,550
Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		14,811	13,556	14,557	[2]	13,989
Total other comprehensive income (loss)		(10)	5	19		(41)
Ending balance		15,064	13,944	15,064		13,944
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(367)	(651)	(419)		(407)
Other comprehensive income before reclassifications: gains (losses)		(16)	2	23		(264)
Amounts reclassified from AOCI: (gains) losses	[3]	12	5	25		27
Total other comprehensive income (loss)		(4)	7	48		(237)
Ending balance		(371)	(644)	(371)		(644)
Deferred Gains and Losses on Derivatives-Hedging Activities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(27)	(79)	(60)		(34)
Other comprehensive income before reclassifications: gains (losses)		(12)	1	20		(44)
Amounts reclassified from AOCI: (gains) losses	[3]			1
Total other comprehensive income (loss)		(12)	1	21		(44)
Ending balance		(39)	(78)	(39)		(78)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		32	37	62		37
Other comprehensive income before reclassifications: gains (losses)		12	19	(19)		28
Amounts reclassified from AOCI: (gains) losses	[3]	(3)	(5)	(2)		(14)
Total other comprehensive income (loss)		9	14	(21)		14
Ending balance		41	51	41		51
Unrealized Gains and Losses on Investment Securities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		4	4	8		5
Other comprehensive income before reclassifications: gains (losses)		3	6	(2)		4
Amounts reclassified from AOCI: (gains) losses	[3]	(1)	(2)			(1)
Total other comprehensive income (loss)		2	4	(2)		3
Ending balance		6	8	6		8
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,335)	(1,402)	(1,359)		(1,421)
Other comprehensive income before reclassifications: gains (losses)			(1)	6		(1)
Amounts reclassified from AOCI: (gains) losses	[3]	26	18	44		37
Total other comprehensive income (loss)		26	17	50		36
Ending balance		(1,309)	(1,385)	(1,309)		(1,385)
Other Comprehensive Loss From Equity Method Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1)	(2)	(1)		(2)
Other comprehensive income before reclassifications: gains (losses)		0	0	0		0
Amounts reclassified from AOCI: (gains) losses	[3]	0	0	0		0
Total other comprehensive income (loss)		0	0	0		0
Ending balance		(1)	(2)	(1)		(2)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,671)	(2,018)	(1,717)		(1,793)
Other comprehensive income before reclassifications: gains (losses)		(4)	20	10		(237)
Amounts reclassified from AOCI: (gains) losses	[3]	35	18	67		50
Total other comprehensive income (loss)		31	38	77		(187)
Ending balance		(1,640)	(1,980)	(1,640)		(1,980)
Accumulated Other Comprehensive Income (Loss) | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(23)	(75)	(52)		(29)
Other comprehensive income before reclassifications: gains (losses)		(9)	7	18		(40)
Amounts reclassified from AOCI: (gains) losses	[3]	(1)	(2)	1		(1)
Total other comprehensive income (loss)		(10)	5	19		(41)
Ending balance		$ (33)	$ (70)	$ (33)		$ (70)

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Virginia Power’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

[3] See table below for details about these reclassifications.