Investments (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended		6 Months Ended
	Mar. 31, 2014	Jan. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Blue Racer
Gain (Loss) on Investments [Line Items]
Increase in equity method investment		$ 155
Write off of goodwill		$ 6
Blue Racer | Pipelines
Gain (Loss) on Investments [Line Items]
Consideration for Northern System	$ 84
Cash proceeds from sale of assets	84
Blue Racer | Pipelines | Other Operations and Maintenance Expense
Gain (Loss) on Investments [Line Items]
Write off of goodwill	3
Gain on sale of assets	59
After tax gain on sale of assets	34
Dominion Gas Holdings, LLC
Gain (Loss) on Investments [Line Items]
Equity in earnings on investments			$ 12	$ 13
Distributions received from investment			12	$ 5
Carrying amount of investment that exceeded share of underlying equity			8		$ 8
Dominion Gas Holdings, LLC | Blue Racer | Pipelines
Gain (Loss) on Investments [Line Items]
Cash proceeds from sale of assets	17
Extinguishment of affiliated current borrowings	67
Dominion Gas Holdings, LLC | Blue Racer | Pipelines | Other Operations and Maintenance Expense
Gain (Loss) on Investments [Line Items]
After tax gain on sale of assets	$ 35
Categories of Investments, Marketable Securities, Trading Securities
Gain (Loss) on Investments [Line Items]
Assets Held-in-trust			104		110
Cost method investments
Gain (Loss) on Investments [Line Items]
Assets Held-in-trust			$ 5		$ 6