Derivatives and Hedge Accounting Activities (Selected Information Related to Gains (Losses) on Cash Flow Hedges Included in AOCI) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (280)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	(19)
Commodity | Gas
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	10
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ 10
Maximum Term	36 months
Commodity | Electricity
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (20)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (20)
Maximum Term	12 months
Commodity | Other
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (3)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (3)
Maximum Term	15 months
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (274)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (5)
Maximum Term	375 months
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ 7
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (1)
Maximum Term	114 months
Virginia Electric and Power Company
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (8)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	(1)
Virginia Electric and Power Company | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	(8)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (1)
Maximum Term	375 months
Dominion Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (24)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	(7)
Dominion Gas Holdings, LLC | Commodity | NGLs
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	(3)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (3)
Maximum Term	15 months
Dominion Gas Holdings, LLC | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ (28)
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (3)
Maximum Term	336 months
Dominion Gas Holdings, LLC | Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
AOCI After-Tax	$ 7
Amounts Expected to be Reclassified to Earnings during the next 12 Months After-Tax	$ (1)
Maximum Term	114 months