Derivatives and Hedge Accounting Activities (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	$ 396	$ 704
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	396	704
Total derivatives, not subject to a master netting or similar arrangement	10	15
Gross Amounts of Recognized Assets, Total	406	719
Derivative Asset	406	719
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	119	348
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	23	34
Net Amounts	254	322
Interest rate | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	31	24
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	31	24
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	29	16
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	2	8
Commodity | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	270	382
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	270	382
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	16	34
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	23	34
Net Amounts	231	314
Commodity | Exchange
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	95	298
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	95	298
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	74	298
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	21	0
Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	128	106
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	128	106
Total derivatives, not subject to a master netting or similar arrangement	22	7
Gross Amounts of Recognized Assets, Total	150	113
Derivative Asset	150	113
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	9	4
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	119	102
Virginia Electric and Power Company | Interest rate | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	8	0
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	8	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	7	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	1	0
Virginia Electric and Power Company | Commodity | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	120	106
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	120	106
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	2	4
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	118	102
Dominion Gas Holdings, LLC
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	9	2
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	9	2
Derivative Asset	9	2
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	1	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	8	2
Dominion Gas Holdings, LLC | Commodity | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	9	2
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	9	2
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	1	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	$ 8	$ 2