Income Taxes (Schedule of Deferred Income Taxes) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Total deferred income tax assets	$ 1,827	$ 1,152
Total deferred income tax liabilities	10,381	8,552
Total net deferred income tax liabilities	8,554	7,400
Total deferred income taxes:
Plant and equipment, primarily depreciation method and basis differences	7,782	6,299
Nuclear decommissioning	1,240	1,158
Deferred state income taxes	747	646
Federal benefit of deferred state income taxes	(261)	(226)
Deferred fuel, purchased energy and gas costs	(25)	(1)
Pension benefits	155	291
Other postretirement benefits	(68)	(15)
Loss and credit carryforwards	(1,547)	(1,004)
Valuation allowances	135	73
Partnership basis differences	688	367
Other	(292)	(188)
Total net deferred income tax liabilities	8,554	7,400
Deferred investment tax credits - regulated operations	48	14
Total deferred taxes and deferred investment tax credits	8,602	7,414
Virginia Electric and Power Company
Income Tax Contingency [Line Items]
Total deferred income tax assets	268	164
Total deferred income tax liabilities	5,323	4,805
Total net deferred income tax liabilities	5,055	4,641
Total deferred income taxes:
Plant and equipment, primarily depreciation method and basis differences	4,604	4,133
Nuclear decommissioning	406	378
Deferred state income taxes	321	302
Federal benefit of deferred state income taxes	(112)	(106)
Deferred fuel, purchased energy and gas costs	(29)	(3)
Pension benefits	(138)	(99)
Other postretirement benefits	49	30
Loss and credit carryforwards	(88)	(53)
Valuation allowances	3	0
Partnership basis differences	0	0
Other	39	59
Total net deferred income tax liabilities	5,055	4,641
Deferred investment tax credits - regulated operations	48	13
Total deferred taxes and deferred investment tax credits	5,103	4,654
Dominion Gas Holdings, LLC
Income Tax Contingency [Line Items]
Total deferred income tax assets	126	129
Total deferred income tax liabilities	2,564	2,343
Total net deferred income tax liabilities	2,438	2,214
Total deferred income taxes:
Plant and equipment, primarily depreciation method and basis differences	1,726	1,541
Nuclear decommissioning	0	0
Deferred state income taxes	204	205
Federal benefit of deferred state income taxes	(71)	(72)
Deferred fuel, purchased energy and gas costs	4	1
Pension benefits	646	613
Other postretirement benefits	(6)	(7)
Loss and credit carryforwards	(5)	(4)
Valuation allowances	0	0
Partnership basis differences	43	41
Other	(103)	(104)
Total net deferred income tax liabilities	2,438	2,214
Deferred investment tax credits - regulated operations	0	0
Total deferred taxes and deferred investment tax credits	$ 2,438	$ 2,214