Derivatives and Hedge Accounting Activities (Schedule of Derivatives not Designated as Hedging Instruments) (Detail) - Derivatives Not Designated as Hedging Instruments - 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 Income on Derivatives	[1],[2]	$ 199	$ 125	$ (46)	$ 501
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	30	(145)	(81)	(243)
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	123	7	184	428
Commodity | Operating Revenue | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	31	6	107	25
Commodity | Electric Fuel and Other Energy-Related Purchases
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	2	(149)	(188)	(267)
Commodity | Electric Fuel and Other Energy-Related Purchases | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	(1)	(151)	(188)	(270)
Commodity | Operation and maintenance
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	0	0	0	2
Commodity | Operation and maintenance | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	0	0	0	2
Commodity | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	0	(7)	0	17
Interest Rate Contract | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	(3)	0	(28)	94
Interest Rate Contract | Interest And Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	$ 77	$ 274	$ (14)	$ 227

[1] Excludes amounts related to foreign currency exchange rate derivatives that are deferred to plant under construction within property, plant and equipment and regulatory assets/liabilities that will begin to amortize once the CVOW Commercial Project is placed in service.

[2] Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in the Companies’ Consolidated Statements of Income.