Derivatives and Hedge Accounting Activities (Gains and Losses on Derivatives in Cash Flow Hedging Relationships) (Detail) - Cash Flow Hedges - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ 6		$ (105)		$ (353)		$ (134)
Amount of Gain (Loss) Reclassified From AOCI to Income		(7)		29		(36)		70
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	14		(131)		(550)		(215)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	2		(15)		(59)	[4]	(24)	[4]
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)		(1)		(1)	[4]	(1)	[4]
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[5]	13		(133)		(552)	[4]	(218)	[4]
Dominion Energy Gas Holdings, LLC
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[6]	1		(32)		(122)		(68)
Amount of Gain (Loss) Reclassified From AOCI to Income		2		2		(6)		(1)
Commodity
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	0		35		0		101
Amount of Gain (Loss) Reclassified From AOCI to Income		9		38		13		95
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	[6]			3				2
Amount of Gain (Loss) Reclassified From AOCI to Income				0				2
Commodity | Dominion Energy Gas Holdings, LLC | Net Income Discontinued Operation
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income								2
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		9		38		16		92
Commodity | Operating Revenue | Dominion Energy Gas Holdings, LLC
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		0
Commodity | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		0				(3)		3
Commodity | Electric Fuel and Other Energy-Related Purchases
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income						0
Interest rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[7]	0		(142)		(336)		(226)
Amount of Gain (Loss) Reclassified From AOCI to Income	[7]	(22)		(13)		(49)		(23)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[7]	14		(131)		(550)		(215)
Interest rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	2	[4]	(15)	[4]	(59)		(24)
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)	[4]	(1)	[4]	(1)		(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[5]	13	[4]	(133)	[4]	(552)		(218)
Interest rate | Dominion Energy Gas Holdings, LLC
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[6],[8]	(4)		(36)		(105)		(60)
Amount of Gain (Loss) Reclassified From AOCI to Income	[8]	(4)		(2)		(6)		(1)
Foreign currency
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[9]	6		2		(17)		(9)
Amount of Gain (Loss) Reclassified From AOCI to Income	[9]	6		4		0		(2)
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	[6],[10]	5		1		(17)		(10)
Amount of Gain (Loss) Reclassified From AOCI to Income	[10]	$ 6		$ 4		$ 0		$ (2)

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

[5] 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.

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

[7] Amounts recorded in Dominion Energy’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 (expense).

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