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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ (10)	$ 25	$ 2	$ 21
Amount of Gain (Loss) Reclassified From AOCI to Income		(11)	(11)	(33)	(32)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(110)	268	20	236
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	(10)	25	2	21
Amount of Gain (Loss) Reclassified From AOCI to Income		0	(1)	0	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(109)	267	20	235
Interest Rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	(10)	25	2	21
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	(11)	(11)	(33)	(32)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	(110)	268	20	236
Interest Rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[3]	(10)	25	2	21
Amount of Gain (Loss) Reclassified From AOCI to Income	[3]	0	(1)	0	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[3]	$ (109)	$ 267	$ 20	$ 235

[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.