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
		Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ 52	$ (359)
Amount of Gain (Loss) Reclassified From AOCI to Income		(17)	(29)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	408	(563)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	43	(61)
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4]	407	(565)
Commodity
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			4
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			6
Commodity | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)	(3)
Commodity | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			1
Interest rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]		(336)
Amount of Gain (Loss) Reclassified From AOCI to Income			(27)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]		(563)
Interest rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3],[5]	43	(61)
Amount of Gain (Loss) Reclassified From AOCI to Income	[5]	(1)	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4],[5]	407	(565)
Interest rate | Interest and Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	52
Amount of Gain (Loss) Reclassified From AOCI to Income		(16)	(25)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	$ 408
Interest rate | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			(2)
Foreign currency
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[6]		(23)
Amount of Gain (Loss) Reclassified From AOCI to Income	[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 Virginia Power’s Consolidated Statements of Income are classified in interest and related charges.

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