Income Taxes (Schedule of Deductible Loss and Credit Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred tax asset	$ 1,547	$ 1,004
Valuation allowance	(135)
Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Deferred tax asset	88	53
Valuation allowance	(3)
Dominion Gas Holdings, LLC
Operating Loss Carryforwards [Line Items]
Deferred tax asset	5	$ 4
Valuation allowance	0
Federal
Operating Loss Carryforwards [Line Items]
Losses, Deductible amount	1,060
Losses, Deferred tax asset	358
Losses, Valuation allowance	0
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	48
Tax Credits, Valuation allowance	0
Federal | Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Losses, Deductible amount	12
Losses, Deferred tax asset	3
Losses, Valuation allowance	0
Federal | Dominion Gas Holdings, LLC
Operating Loss Carryforwards [Line Items]
Losses, Deductible amount	14
Losses, Deferred tax asset	4
Losses, Valuation allowance	0
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	1
Tax Credits, Valuation allowance	0
Federal | Investment Credits
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	708
Tax Credits, Valuation allowance	0
Federal | Investment Credits | Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	40
Tax Credits, Valuation allowance	0
Federal | Federal production credits
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	102
Tax Credits, Valuation allowance	0
Federal | Federal production credits | Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	35
Tax Credits, Valuation allowance	0
State
Operating Loss Carryforwards [Line Items]
Losses, Deductible amount	1,383
Losses, Deferred tax asset	102
Losses, Valuation allowance	(59)
Tax credits, Deductible amount	0
State minimum tax credits	135
Tax Credits, Valuation allowance	0
State | Investment Credits
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	94
Tax Credits, Valuation allowance	(76)
State | Investment Credits | Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Tax credits, Deductible amount	0
Tax credits, Deferred tax asset	10
Tax Credits, Valuation allowance	$ (3)