Income Taxes (Schedule of Deferred Income Taxes) (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred income taxes:
Total deferred income tax assets	$ 3,736,000,000	$ 2,748,000,000
Total deferred income tax liabilities	9,883,000,000	7,813,000,000
Total net deferred income tax liabilities	6,147,000,000	5,065,000,000
Plant and equipment, primarily depreciation method and basis differences	6,616,000,000	4,933,000,000
Excess deferred income taxes	(1,306,000,000)	(993,000,000)
Unrecovered NND Project costs	553	0
DESC rate refund	(169)	0
Toshiba Settlement	(219)	0
Nuclear decommissioning	909,000,000	815,000,000
Deferred state income taxes	863,000,000	626,000,000
Federal benefit of deferred state income taxes	(184,000,000)	(132,000,000)
Deferred fuel, purchased energy and gas costs	30,000,000	60,000,000
Pension benefits	174,000,000	81,000,000
Other postretirement benefits	(37,000,000)	(5,000,000)
Loss and credit carryforwards	(1,832,000,000)	(1,546,000,000)
Valuation allowances	161,000,000	158,000,000
Partnership basis differences	823,000,000	1,135,000,000
Other	(235,000,000)	(67,000,000)
Total net deferred income tax liabilities	6,147,000,000	5,065,000,000
Deferred Investment Tax Credits - Regulated Operations	130,000,000	51,000,000
Total Deferred Taxes and Deferred Investment Tax Credits	6,277,000,000	5,116,000,000
Virginia Electric and Power Company
Deferred income taxes:
Total deferred income tax assets	1,207,000,000	1,054,000,000
Total deferred income tax liabilities	4,058,000,000	4,020,000,000
Total net deferred income tax liabilities	2,851,000,000	2,966,000,000
Plant and equipment, primarily depreciation method and basis differences	3,359,000,000	3,367,000,000
Excess deferred income taxes	(672,000,000)	(678,000,000)
Unrecovered NND Project costs	0	0
DESC rate refund	0	0
Toshiba Settlement	0	0
Nuclear decommissioning	290,000,000	273,000,000
Deferred state income taxes	302,000,000	284,000,000
Federal benefit of deferred state income taxes	(63,000,000)	(60,000,000)
Deferred fuel, purchased energy and gas costs	1,000,000	59,000,000
Pension benefits	(153,000,000)	(132,000,000)
Other postretirement benefits	62,000,000	55,000,000
Loss and credit carryforwards	(280,000,000)	(183,000,000)
Valuation allowances	5,000,000	5,000,000
Partnership basis differences	0	0
Other	0	(24,000,000)
Total net deferred income tax liabilities	2,851,000,000	2,966,000,000
Deferred Investment Tax Credits - Regulated Operations	111,000,000	51,000,000
Total Deferred Taxes and Deferred Investment Tax Credits	2,962,000,000	3,017,000,000
Dominion Energy Gas Holdings, LLC
Deferred income taxes:
Total deferred income tax assets	206,000,000	296,000,000
Total deferred income tax liabilities	1,494,000,000	1,626,000,000
Total net deferred income tax liabilities	1,288,000,000	1,330,000,000
Plant and equipment, primarily depreciation method and basis differences	742,000,000	671,000,000
Excess deferred income taxes	(149,000,000)	(156,000,000)
Unrecovered NND Project costs	0	0
DESC rate refund	0	0
Toshiba Settlement	0	0
Nuclear decommissioning	0	0
Deferred state income taxes	199,000,000	203,000,000
Federal benefit of deferred state income taxes	(42,000,000)	(43,000,000)
Deferred fuel, purchased energy and gas costs	0	(1,000,000)
Pension benefits	154,000,000	134,000,000
Other postretirement benefits	(6,000,000)	(3,000,000)
Loss and credit carryforwards	(1,000,000)	(5,000,000)
Valuation allowances	1,000,000	6,000,000
Partnership basis differences	423,000,000	570,000,000
Other	(33,000,000)	(46,000,000)
Total net deferred income tax liabilities	1,288,000,000	1,330,000,000
Deferred Investment Tax Credits - Regulated Operations	0	0
Total Deferred Taxes and Deferred Investment Tax Credits	$ 1,288,000,000	$ 1,330,000,000