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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ 4	$ 8	$ 12	$ (4)
Amount of Gain (Loss) Reclassified From AOCI to Income		(11)	(10)	(22)	(21)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	42	88	130	(32)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	4	8	12	(4)
Amount of Gain (Loss) Reclassified From AOCI to Income		0	0	0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	41	88	129	(32)
Interest Rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	4	8	12	(4)
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(11)	(10)	(22)	(21)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	42	88	130	(32)
Interest Rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	4	8	12	(4)
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	0	0	0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	$ 41	$ 88	$ 129	$ (32)

[1] Amounts deferred into AOCI have no associated effect in the Companies’ 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 the Companies’ Consolidated Statements of Income.

[3] Amounts recorded in the Companies’ Consolidated Statements of Income are classified in interest and related charges.