Quarterly Financial and Common Stock Data (Unaudited) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015
Facilities Subject to Coal Combustion Residual Final Rule
Condensed Financial Statements, Captions [Line Items]
Charge related to future ash pond and landfill closure costs	$ 122
Virginia Electric and Power Company | Deferred Fuel Costs | Virginia Regulation
Condensed Financial Statements, Captions [Line Items]
Write off of deferred fuel cost, net of tax					$ 52
Virginia Electric and Power Company | Facilities Subject to Coal Combustion Residual Final Rule
Condensed Financial Statements, Captions [Line Items]
Charge related to future ash pond and landfill closure costs	$ 121	$ 32		$ 28
Dominion Gas Holdings, LLC | Oil and Gas Properties
Condensed Financial Statements, Captions [Line Items]
After tax gain on sale			$ 29		$ 43