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		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1]	$ 16	$ 22	$ 131	$ 90
Amount of Gain (Loss) Reclassified From AOCI to Income		25	55	91	229
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(26)	(16)	(60)	(258)
Virginia Electric and Power Company
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[3]	(3)	(2)	(8)	(26)
Amount of Gain (Loss) Reclassified From AOCI to Income		0	0	(1)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4]	(26)	(16)	(60)	(258)
Dominion Energy Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5]	2	12	5	(11)
Amount of Gain (Loss) Reclassified From AOCI to Income		7	3	8	5
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1]	8	7	139	193
Amount of Gain (Loss) Reclassified From AOCI to Income		31	62	115	249
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0	0	0
Commodity | Dominion Energy Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5]	(10)		(5)	(7)
Amount of Gain (Loss) Reclassified From AOCI to Income		(2)	1	(4)	6
Commodity | Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		32	64	114	266
Commodity | Operating Revenue | Dominion Energy Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(2)	1	(4)	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)	(1)	1	(8)
Commodity | Purchased Gas
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			(1)		(9)
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1],[6]	(4)	3	(18)	(107)
Amount of Gain (Loss) Reclassified From AOCI to Income	[6]	(16)	(10)	(39)	(21)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[6]	(26)	(16)	(60)	(258)
Interest rate | Virginia Electric and Power Company
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[3],[7]	(3)	(2)	(8)	(26)
Amount of Gain (Loss) Reclassified From AOCI to Income	[7]	0	0	(1)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4],[7]	(26)	(16)	(60)	(258)
Interest rate | Dominion Energy Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5],[8]	0			(8)
Amount of Gain (Loss) Reclassified From AOCI to Income	[8]	(1)	(1)	(3)	(2)
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[1],[9]	12	12	10	4
Amount of Gain (Loss) Reclassified From AOCI to Income	[9]	10	3	15	1
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[9]	0	0	0	0
Foreign currency | Dominion Energy Gas Holdings, LLC
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	[5],[10]	12	12	10	4
Amount of Gain (Loss) Reclassified From AOCI to Income	[10]	$ 10	$ 3	$ 15	$ 1

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

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

[4] 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.

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

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

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

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

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

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