Derivatives and Hedge Accounting Activities (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	$ 347	$ 379
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	347	379
Total derivatives, not subject to a master netting or similar arrangement	7	9
Gross Amounts of Recognized Assets, Total	354	388
Derivative Asset	354	388
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	94	141
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	253	238
Commodity \| Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	231	217
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	231	217
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	16	37
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	215	180
Commodity \| Exchange
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	91	138
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	91	138
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	63	82
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	28	56
Interest rate \| Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	25	24
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	25	24
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	15	22
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	10	2
Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	127	114
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	127	114
Total derivatives, not subject to a master netting or similar arrangement	36	13
Gross Amounts of Recognized Assets, Total	163	127
Derivative Asset	163	127
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	7	13
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	120	101
Virginia Electric and Power Company \| Commodity \| Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	127	101
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	127	101
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	7	3
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	120	98
Virginia Electric and Power Company \| Interest rate \| Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	0	13
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	0	13
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	0	10
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	0	3
Dominion Gas Holdings, LLC
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	3	11
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	3	11
Derivative Asset	3	11
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	3	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	0	11
Dominion Gas Holdings, LLC \| Commodity \| Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	3	11
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	3	11
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	3	0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	0	0
Net Amounts	$ 0	$ 11

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