Income Taxes (Schedule of Deferred Income Taxes) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred income taxes:
Total deferred income tax assets	$ 2,748	$ 2,686
Total deferred income tax liabilities	7,813	7,158
Total net deferred income tax liabilities	5,065	4,472
Plant and equipment, primarily depreciation method and basis differences	4,933	5,056
Excess deferred income taxes	(993)	(1,050)
Nuclear decommissioning	815	829
Deferred state income taxes	626	834
Federal benefit of deferred state income taxes	(132)	(175)
Deferred fuel, purchased energy and gas costs	60	1
Pension benefits	81	141
Other postretirement benefits	(5)	(51)
Loss and credit carryforwards	(1,546)	(1,536)
Valuation allowances	158	146
Partnership basis differences	1,135	473
Other	(67)	(196)
Total net deferred income tax liabilities	5,065	4,472
Deferred Investment Tax Credits - Regulated Operations	51	51
Total Deferred Taxes and Deferred Investment Tax Credits	5,116	4,523
Virginia Electric and Power Company
Deferred income taxes:
Total deferred income tax assets	1,054	923
Total deferred income tax liabilities	4,020	3,600
Total net deferred income tax liabilities	2,966	2,677
Plant and equipment, primarily depreciation method and basis differences	3,367	2,969
Excess deferred income taxes	(678)	(687)
Nuclear decommissioning	273	260
Deferred state income taxes	284	378
Federal benefit of deferred state income taxes	(60)	(79)
Deferred fuel, purchased energy and gas costs	59	(3)
Pension benefits	(132)	(104)
Other postretirement benefits	55	44
Loss and credit carryforwards	(183)	(111)
Valuation allowances	5	5
Other	(24)	5
Total net deferred income tax liabilities	2,966	2,677
Deferred Investment Tax Credits - Regulated Operations	51	51
Total Deferred Taxes and Deferred Investment Tax Credits	3,017	2,728
Dominion Energy Gas Holdings, LLC
Deferred income taxes:
Total deferred income tax assets	318	320
Total deferred income tax liabilities	1,783	1,774
Total net deferred income tax liabilities	1,465	1,454
Plant and equipment, primarily depreciation method and basis differences	1,170	1,132
Excess deferred income taxes	(254)	(244)
Deferred state income taxes	175	227
Federal benefit of deferred state income taxes	(37)	(48)
Deferred fuel, purchased energy and gas costs	1	2
Pension benefits	431	419
Other postretirement benefits	(1)	(2)
Loss and credit carryforwards	(7)	(4)
Valuation allowances	12	3
Partnership basis differences	26	26
Other	(51)	(57)
Total net deferred income tax liabilities	1,465	1,454
Total Deferred Taxes and Deferred Investment Tax Credits	$ 1,465	$ 1,454