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		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	$ 34	$ 208	$ 376	$ 135
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	(61)	37	(98)	53
Commodity Contract | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	26	(272)	421	(602)
Commodity Contract | Operating Revenue | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	10	(88)	19	(129)
Commodity Contract | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	0	3	94	5
Commodity Contract | Electric Fuel and Other Energy-Related Purchases
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	(73)	137	(118)	196
Commodity Contract | 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]	(73)	125	(119)	182
Commodity Contract | Operation and maintenance
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	2	0	2	0
Commodity Contract | 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]	2	0	2	0
Interest Rate Contract | Interest And Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[2]	$ 79	$ 340	$ (23)	$ 536

[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.