Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Provision for current income taxes	$ (70)	$ 51	$ 3
Deferred income taxes charged to common shareholders' equity	96
Unrecognized tax benefits that would impact effective tax rate	45	69	77
Increase (decrease) in unrecognized tax benefits (less than $1 million)	(18)	(6)	(47)
Maximum
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized tax benefits due to settlement negotiations and expiration of statutes of limitations	25
Amount that earnings could potentially increase if changes were to occur	20
Federal
Operating Loss Carryforwards [Line Items]
Federal tax credits	129
Realizable domestic production activities deduction	17
Federal | IRS
Operating Loss Carryforwards [Line Items]
Benefit related to carryback recognized		20
Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Provision for current income taxes	258	408	152
Unrecognized tax benefits that would impact effective tax rate	9	8	8
Increase (decrease) in unrecognized tax benefits (less than $1 million)	1	1
Virginia Electric and Power Company | Maximum
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized tax benefits due to settlement negotiations and expiration of statutes of limitations	3
Amount that earnings could potentially increase if changes were to occur	3
Dominion Gas Holdings, LLC
Operating Loss Carryforwards [Line Items]
Provision for current income taxes	(23)	120	118
Unrecognized tax benefits that would impact effective tax rate	5	19	19
Increase (decrease) in unrecognized tax benefits (less than $1 million)	(11)	$ 1	$ 1
Dominion Gas Holdings, LLC | Maximum
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized tax benefits due to settlement negotiations and expiration of statutes of limitations	7
Amount that earnings could potentially increase if changes were to occur	5
Dominion Midstream Partners, LP | Questar Pipeline, LLC | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Federal
Operating Loss Carryforwards [Line Items]
Provision for current income taxes	$ 212