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, 2024	Mar. 31, 2023
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ 8	$ (12)
Amount of Gain (Loss) Reclassified From AOCI to Income		(11)	(11)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	88	(120)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	8	(12)
Amount of Gain (Loss) Reclassified From AOCI to Income		(0)	(0)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	88	(120)
Interest Rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	8	(12)
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(11)	(11)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	88	(120)
Interest Rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	8	(12)
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(0)	(0)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	$ 88	$ (120)

[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 Statement of Income are classified in interest and related charges.