Derivatives and Hedge Accounting Activities (Gains and Losses on Derivatives in Cash Flow Hedging Relationships) (Details) - Cash Flow Hedges - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1]	$ 70	$ 86
Amount of Gain (Loss) Reclassified From AOCI to Income		37	102
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	8	(133)
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1]	87	173
Amount of Gain (Loss) Reclassified From AOCI to Income		62	105
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0
Commodity | Operating revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		62	114
Commodity | Purchased gas
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		1	(6)
Commodity | Electric fuel and other energy-related purchases
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)	(3)
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1],[3]	1	(87)
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(11)	(3)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	8	(133)
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1],[4]	(18)
Amount of Gain (Loss) Reclassified From AOCI to Income	[4]	(14)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[4]	0
Virginia Electric and Power Company
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5]	0	(14)
Amount of Gain (Loss) Reclassified From AOCI to Income		0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[6]	8	(133)
Virginia Electric and Power Company | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5],[7]	0	(14)
Amount of Gain (Loss) Reclassified From AOCI to Income	[7]	0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[6],[7]	8	(133)
Dominion Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[8]	(16)	(10)
Amount of Gain (Loss) Reclassified From AOCI to Income		(18)	4
Dominion Gas Holdings, LLC | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[8]	2	(1)
Amount of Gain (Loss) Reclassified From AOCI to Income		(3)	4
Dominion Gas Holdings, LLC | Commodity | Operating revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(3)	4
Dominion Gas Holdings, LLC | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[8],[9]	0	(9)
Amount of Gain (Loss) Reclassified From AOCI to Income	[9]	(1)	$ 0
Dominion Gas Holdings, LLC | Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[8],[10]	(18)
Amount of Gain (Loss) Reclassified From AOCI to Income	[10]	$ (14)

[1] Amounts deferred into AOCI have no associated effect in Dominion’s Consolidated Statements of Income.

[2] Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Dominion’s Consolidated Statements of Income.

[3] Amounts recorded in Dominion’s Consolidated Statements of Income are classified in interest and related charges.

[4] Amounts recorded in Dominion’s Consolidated Statements of Income are classified in other income.

[5] Amounts deferred into AOCI have no associated effect in Virginia Power’s Consolidated Statements of Income.

[6] Represents net derivative activity deferred into and amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Virginia Power’s Consolidated Statements of Income.

[7] Amounts recorded in Virginia Power’s Consolidated Statements of Income are classified in interest and related charges.

[8] Amounts deferred into AOCI have no associated effect in Dominion Gas' Consolidated Statements of Income.

[9] Amounts recorded in Dominion Gas' Consolidated Statements of Income are classified in interest and related charges.

[10] Amounts recorded in Dominion Gas' Consolidated Statements of Income are classified in other income.