Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Investment tax credits		$ (134)	$ (152)	$ (48)
Unrecognized tax benefits that would impact effective tax rate		69	77	126
Increase (decrease) in unrecognized tax benefits		(6)	(47)	(29)
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized tax benefits due to settlement negotiations and expiration of statutes of limitations	$ 30
Amount that earnings could potentially increase if changes were to occur	15
Federal | IRS
Operating Loss Carryforwards [Line Items]
Benefit related to carryback recognized		20
Operating loss carryforward		594
Investment tax credits		407
Tax credits		89
Payment after conclusion of audit				46
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		1,600
Carryforwards valuation allowance		1,100
General Business | State
Operating Loss Carryforwards [Line Items]
Tax credits		145
Investment Credits | State
Operating Loss Carryforwards [Line Items]
Tax credits		40
Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
Investment tax credits		(11)	0	0
Unrecognized tax benefits that would impact effective tax rate		8	8	8
Increase (decrease) in unrecognized tax benefits		1	1	4
Virginia Electric and Power Company | Federal | IRS
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		7
Tax credits		38
Virginia Electric and Power Company | Investment Credits | State
Operating Loss Carryforwards [Line Items]
Amount of tax credits		9
Dominion Gas Holdings, LLC
Operating Loss Carryforwards [Line Items]
Investment tax credits		0	0	0
Unrecognized tax benefits that would impact effective tax rate		19	19	19
Increase (decrease) in unrecognized tax benefits		1	$ 1	$ 1
Dominion Gas Holdings, LLC | Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Decrease in Unrecognized tax benefits due to settlement negotiations and expiration of statutes of limitations	22
Amount that earnings could potentially increase if changes were to occur	$ 10
Dominion Gas Holdings, LLC | Federal | IRS
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		$ 10