Accumulated Other Comprehensive Income (Schedule of Changes in AOCI by Component Net of Tax) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021		Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	$ 26,117
Total other comprehensive income (loss)		46		$ (225)
Ending balance		26,699
Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		14,557	[2]	13,989
Total other comprehensive income (loss)		29		(46)
Ending balance		14,811		13,556
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(419)		(407)
Other comprehensive income before reclassifications: gains (losses)		39		(266)
Amounts reclassified from AOCI: (gains) losses	[3]	13		22
Total other comprehensive income (loss)		52		(244)
Ending balance		(367)		(651)
Deferred Gains and Losses on Derivatives-Hedging Activities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(60)		(34)
Other comprehensive income before reclassifications: gains (losses)		32		(45)
Amounts reclassified from AOCI: (gains) losses	[4]	1
Total other comprehensive income (loss)		33		(45)
Ending balance		(27)		(79)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		62		37
Other comprehensive income before reclassifications: gains (losses)		(31)		9
Amounts reclassified from AOCI: (gains) losses	[3]	1		(9)
Total other comprehensive income (loss)		(30)
Ending balance		32		37
Unrealized Gains and Losses on Investment Securities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		8		5
Other comprehensive income before reclassifications: gains (losses)		(5)		(2)
Amounts reclassified from AOCI: (gains) losses	[4]	1		1
Total other comprehensive income (loss)		(4)		(1)
Ending balance		4		4
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,359)		(1,421)
Other comprehensive income before reclassifications: gains (losses)		6
Amounts reclassified from AOCI: (gains) losses	[3]	18		19
Total other comprehensive income (loss)		24		19
Ending balance		(1,335)		(1,402)
Other Comprehensive Loss From Equity Method Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1)		(2)
Other comprehensive income before reclassifications: gains (losses)		0		0
Amounts reclassified from AOCI: (gains) losses	[3]	0		0
Total other comprehensive income (loss)		0		0
Ending balance		(1)		(2)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,717)		(1,793)
Other comprehensive income before reclassifications: gains (losses)		14		(257)
Amounts reclassified from AOCI: (gains) losses	[3]	32		32
Total other comprehensive income (loss)		46		(225)
Ending balance		(1,671)		(2,018)
Accumulated Other Comprehensive Income (Loss) | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(52)		(29)
Other comprehensive income before reclassifications: gains (losses)		27		(47)
Amounts reclassified from AOCI: (gains) losses	[4]	2		1
Total other comprehensive income (loss)		29		(46)
Ending balance		$ (23)		$ (75)

[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.

[4] See table below for details about these reclassifications