Derivatives and Hedge Accounting Activities (Selected Information Related to Gains (Losses) on Cash Flow Hedges Included in AOCI) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (206)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	38
Commodity | Gas Energy Contract
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	(8)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (7)
Maximum Term	25 months
Commodity | Electricity Energy Contract
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ 67
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ 50
Maximum Term	15 months
Commodity | Other Energy Contract
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ 5
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ 4
Maximum Term	18 months
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (270)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (9)
Maximum Term	387 months
Dominion Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (21)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	3
Dominion Gas Holdings, LLC | Commodity | NGLs
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	5
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ 4
Maximum Term	18 months
Dominion Gas Holdings, LLC | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (26)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (1)
Maximum Term	351 months