Income Taxes (Income Tax Expense for Continuing Operations Including Noncontrolling Interests) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal		$ 32	$ (45)	$ (1)
State		103	108	(26)
Total current expense (benefit)		135	63	(27)
Deferred:
2017 Tax Reform Act impact	[1]		46	(851)
Taxes before operating loss carryforwards, investment tax credits and tax reform		182	436	739
Tax utilization expense (benefit) of operating loss carryforwards		119	92	174
Investment tax credits		(51)	(56)	(200)
State		(93)	(1)	132
Total deferred expense (benefit)		157	517	(6)
Investment tax credit-gross deferral		62	2	5
Investment tax credit-amortization		(3)	(2)	(2)
Total income tax expense (benefit)		351	580	(30)
Virginia Electric and Power Company
Current:
Federal		286	36	432
State		58	40	73
Total current expense (benefit)		344	76	505
Deferred:
2017 Tax Reform Act impact	[1]	0	21	(93)
Taxes before operating loss carryforwards, investment tax credits and tax reform		(128)	199	319
Tax utilization expense (benefit) of operating loss carryforwards		0	0	4
Investment tax credits		(34)	(51)	(23)
State		22	55	59
Total deferred expense (benefit)		(140)	224	266
Investment tax credit-gross deferral		62	2	5
Investment tax credit-amortization		(2)	(2)	(2)
Total income tax expense (benefit)		264	300	774
Dominion Energy Gas Holdings, LLC
Current:
Federal		130	(227)	75
State		17	31	13
Total current expense (benefit)		147	(196)	88
Deferred:
2017 Tax Reform Act impact	[1]		(6)	(246)
Taxes before operating loss carryforwards, investment tax credits and tax reform		(36)	343	88
Tax utilization expense (benefit) of operating loss carryforwards		0	0	0
Investment tax credits		0	0	0
State		(10)	(17)	5
Total deferred expense (benefit)		(46)	320	(153)
Investment tax credit-gross deferral		0	0	0
Investment tax credit-amortization		0	0	0
Total income tax expense (benefit)		$ 101	$ 124	$ (65)

[1] The 2017 Tax Reform Act impact for Dominion Energy Gas includes an expense of $8 million for the year ended December 31, 2018 and a benefit of $93 million for the year ended December 31, 2017 arising from discontinued operations.