Accumulated Other Comprehensive Income (Schedule of Changes in AOCI by Component Net of Tax) (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]					$ 31,994
Total other comprehensive income (loss)		$ 38		$ 48		(187)		$ 17
Ending balance		28,871				28,871
Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		13,556		12,944		13,989	[2]	13,047
Total other comprehensive income (loss)		5		(9)		(41)		(14)
Ending balance		13,944		12,964		13,944		12,964
Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss)		0		5		(84)		(18)
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(651)		(290)		(407)		(235)
Other comprehensive income before reclassifications: gains (losses)		2		(78)		(264)		(102)
Amounts reclassified from AOCI: (gains) losses	[3]	5		(21)		27		(52)
Total other comprehensive income (loss)		7		(99)		(237)		(154)
Ending balance		(644)		(389)		(644)		(389)
Deferred Gains and Losses on Derivatives-Hedging Activities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(79)		(20)		(34)		(13)
Other comprehensive income before reclassifications: gains (losses)		1		(11)		(44)		(18)
Amounts reclassified from AOCI: (gains) losses	[4]	0		1		0		1
Total other comprehensive income (loss)		1		(10)		(44)		(17)
Ending balance		(78)		(30)		(78)		(30)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(166)		(48)		(81)		(25)
Other comprehensive income before reclassifications: gains (losses)				(24)		(91)		(51)
Amounts reclassified from AOCI: (gains) losses		(2)	[3]	(2)	[3]	4	[5]	1	[5]
Total other comprehensive income (loss)		(2)		(26)		(87)		(50)
Ending balance		(168)		(74)		(168)		(74)
Less other comprehensive income (loss) attributable to noncontrolling interest								(1)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		37		18		37		2
Other comprehensive income before reclassifications: gains (losses)		19		13		28		29
Amounts reclassified from AOCI: (gains) losses	[3]	(5)		(1)		(14)		(1)
Total other comprehensive income (loss)		14		12		14		28
Ending balance		51		30		51		30
Unrealized Gains and Losses on Investment Securities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		4		3		5		1
Other comprehensive income before reclassifications: gains (losses)		6		2		4		4
Amounts reclassified from AOCI: (gains) losses	[4]	(2)		(1)		(1)		(1)
Total other comprehensive income (loss)		4		1		3		3
Ending balance		8		4		8		4
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,402)		(1,457)		(1,421)		(1,465)
Other comprehensive income before reclassifications: gains (losses)		(1)		113		(1)		113
Amounts reclassified from AOCI: (gains) losses	[3]	18		22		37		30
Total other comprehensive income (loss)		17		135		36		143
Ending balance		(1,385)		(1,322)		(1,385)		(1,322)
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(105)		(143)		(106)		(144)
Other comprehensive income before reclassifications: gains (losses)				29		0		29
Amounts reclassified from AOCI: (gains) losses		2	[3]	2	[3]	3	[5]	3	[5]
Total other comprehensive income (loss)		2		31		3		32
Ending balance		(103)		(112)		(103)		(112)
Less other comprehensive income (loss) attributable to noncontrolling interest								0
Other Comprehensive Loss From Equity Method Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(2)		(2)		(2)		(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		(2)		(2)		(2)		(2)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(2,018)		(1,731)		(1,793)		(1,700)
Other comprehensive income before reclassifications: gains (losses)		20		48		(237)		40
Amounts reclassified from AOCI: (gains) losses	[3]	18		0		50		(23)
Total other comprehensive income (loss)		38		48		(187)		17
Ending balance		(1,980)		(1,683)		(1,980)		(1,683)
Accumulated Other Comprehensive Income (Loss) | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(75)		(17)		(29)		(12)
Other comprehensive income before reclassifications: gains (losses)		7		(9)		(40)		(14)
Amounts reclassified from AOCI: (gains) losses	[4]	(2)		0		(1)		0
Total other comprehensive income (loss)		5		(9)		(41)		(14)
Ending balance		(70)		(26)		(70)		(26)
Accumulated Other Comprehensive Income (Loss) | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(271)		(191)		(187)		(169)
Other comprehensive income before reclassifications: gains (losses)				5		(91)		(22)
Amounts reclassified from AOCI: (gains) losses		0	[3]	0	[3]	7	[5]	4	[5]
Total other comprehensive income (loss)		0		5		(84)		(18)
Ending balance		$ (271)		$ (186)		$ (271)		(186)
Less other comprehensive income (loss) attributable to noncontrolling interest								$ (1)

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 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. Virginia Power’s reclassifications out of AOCI were immaterial for both the three and six months ended June 30, 2019

[5] See table below for details about these reclassifications