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			9 Months Ended
		Sep. 30, 2021		Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ (2)		$ 14	$ 29		$ (339)
Amount of Gain (Loss) Reclassified From AOCI to Income		(14)		(251)	(47)		(287)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	9		62	198		(488)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	(2)		6	24		(53)
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)		(1)	(2)		(2)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4]	8		60	194		(492)
Commodity contracts
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income				8	(1)		21
Commodity contracts | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income				8			22
Commodity contracts | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income							2
Commodity contracts | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income					(1)		(3)
Interest rate contracts
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	(2)	[5]	8	29	[5]	(328)
Amount of Gain (Loss) Reclassified From AOCI to Income		(14)	[5]	(253)	(46)	[5]	(302)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	9	[5]	62	198	[5]	(488)
Interest rate contracts | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3],[6]	(2)		6	24		(53)
Amount of Gain (Loss) Reclassified From AOCI to Income	[6]	(1)		(1)	(2)		(2)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4],[6]	$ 8		60	$ 194		(492)
Interest rate contracts | Interest and Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income				(23)			(66)
Interest rate contracts | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income				(230)			(236)
Foreign Exchange Contract
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[7]			6			(11)
Amount of Gain (Loss) Reclassified From AOCI to Income	[7]			$ (6)			$ (6)

[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 recorded in Dominion Energy’s Consolidated Statement of Income are classified in interest and related charges.

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

[7] Amounts recorded in Dominion Energy’s Consolidated Statement of Income are classified in discontinued operations.