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, 2025	Mar. 31, 2024
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ (21)	$ 8
Amount of Gain (Loss) Reclassified From AOCI to Income		(10)	(11)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(100)	88
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	(9)	8
Amount of Gain (Loss) Reclassified From AOCI to Income		0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(101)	88
Interest Rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	(21)	8
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(10)	(11)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	(100)	88
Interest Rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	(9)	8
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	0	0
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	$ (101)	$ 88

[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.