Goodwill and Intangible Assets (Components of Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 955	$ 942
Accumulated Amortization	337	372
Virginia Electric and Power Company
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	326	301
Accumulated Amortization	101	88
Dominion Gas Holdings, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	147	211
Accumulated Amortization	49	128
Software, licenses and other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	955	942
Accumulated Amortization	337	372
Software, licenses and other | Virginia Electric and Power Company
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	326	301
Accumulated Amortization	101	88
Software, licenses and other | Dominion Gas Holdings, LLC
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	147	211
Accumulated Amortization	$ 49	$ 128