Accumulated Other Comprehensive Income (Schedule of Changes in AOCI by Component Net of Tax) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	$ 31,994
Total other comprehensive loss		(225)		$ (31)
Ending balance		30,726
Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		13,989	[2]	13,047
Total other comprehensive loss		(46)		(5)
Ending balance		13,556		12,944
Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive loss		(84)		(23)
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(407)		(235)
Other comprehensive income before reclassifications: gains (losses)		(266)		(24)
Amounts reclassified from AOCI: (gains) losses	[3]	22		(31)
Total other comprehensive loss		(244)		(55)
Ending balance		(651)		(290)
Deferred Gains and Losses on Derivatives-Hedging Activities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(34)		(13)
Other comprehensive income before reclassifications: gains (losses)		(45)		(7)
Total other comprehensive loss		(45)		(7)
Ending balance		(79)		(20)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(81)		(25)
Other comprehensive income before reclassifications: gains (losses)		(91)		(27)
Amounts reclassified from AOCI: (gains) losses	[3]	6		3
Total other comprehensive loss		(85)		(24)
Less other comprehensive income (loss) attributable to noncontrolling interest				(1)
Ending balance		(166)		(48)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		37		2
Other comprehensive income before reclassifications: gains (losses)		9		16
Amounts reclassified from AOCI: (gains) losses	[3]	(9)
Total other comprehensive loss				16
Ending balance		37		18
Unrealized Gains and Losses on Investment Securities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		5		1
Other comprehensive income before reclassifications: gains (losses)		(2)		2
Amounts reclassified from AOCI: (gains) losses	[3]	1
Total other comprehensive loss		(1)		2
Ending balance		4		3
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,421)		(1,465)
Amounts reclassified from AOCI: (gains) losses	[3]	19		8
Total other comprehensive loss		19		8
Ending balance		(1,402)		(1,457)
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(106)		(144)
Amounts reclassified from AOCI: (gains) losses	[3]	1		1
Total other comprehensive loss		1		1
Ending balance		(105)		(143)
Other Comprehensive Loss From Equity Method Investees
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(2)		(2)
Ending balance		(2)		(2)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,793)		(1,700)
Other comprehensive income before reclassifications: gains (losses)		(257)		(8)
Amounts reclassified from AOCI: (gains) losses	[3]	32		(23)
Total other comprehensive loss		(225)		(31)
Ending balance		(2,018)		(1,731)
Accumulated Other Comprehensive Income (Loss) | Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(29)		(12)
Other comprehensive income before reclassifications: gains (losses)		(47)		(5)
Amounts reclassified from AOCI: (gains) losses	[3]	1
Total other comprehensive loss		(46)		(5)
Ending balance		(75)		(17)
Accumulated Other Comprehensive Income (Loss) | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(187)		(169)
Other comprehensive income before reclassifications: gains (losses)		(91)		(27)
Amounts reclassified from AOCI: (gains) losses	[3]	7		4
Total other comprehensive loss		(84)		(23)
Less other comprehensive income (loss) attributable to noncontrolling interest				(1)
Ending balance		$ (271)		$ (191)

[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.