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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ 14	$ (144)	$ (339)	$ (278)
Amount of Gain (Loss) Reclassified From AOCI to Income		(251)	7	(287)	77
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	62	(190)	(488)	(405)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	6	(21)	(53)	(45)
Amount of Gain (Loss) Reclassified From AOCI to Income		(1)	0	(2)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4]	60	(190)	(492)	(408)
Commodity
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	0	(5)	0	96
Amount of Gain (Loss) Reclassified From AOCI to Income		8	33	21	128
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0	0	0
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		8	34	22	123
Commodity | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income			(2)	(3)	1
Commodity | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]		0	0	0
Amount of Gain (Loss) Reclassified From AOCI to Income			1	2	4
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]		0	0	0
Interest rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	8	(124)	(328)	(350)
Amount of Gain (Loss) Reclassified From AOCI to Income		(253)	(14)	(302)	(37)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	62	(190)	(488)	(405)
Interest rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3],[5]	6	(21)	(53)	(45)
Amount of Gain (Loss) Reclassified From AOCI to Income	[5]	(1)	0	(2)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4],[5]	60	(190)	(492)	(408)
Interest rate | Interest and Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	0	0	0	0
Amount of Gain (Loss) Reclassified From AOCI to Income		(23)	(12)	(66)	(35)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0	0	0
Interest rate | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	0	0	0	0
Amount of Gain (Loss) Reclassified From AOCI to Income		(230)	(2)	(236)	(2)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0	0	0
Foreign currency
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[6]	6	(15)	(11)	(24)
Amount of Gain (Loss) Reclassified From AOCI to Income	[6]	(6)	(12)	(6)	(14)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[6]	$ 0	$ 0	$ 0	$ 0

[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 Statements of Income are classified in discontinued operations.