Goodwill and Intangible Assets (Components of Intangible Assets) (Detail) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Software, Licenses and Other
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 1,645	$ 1,477
Accumulated Amortization		708	627
Renewable energy credits and RGGI allowances
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	199	708
Accumulated Amortization	[1]	0	613
Virginia Electric and Power Company | Software, Licenses and Other
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		911	802
Accumulated Amortization		291	243
Virginia Electric and Power Company | Renewable energy credits and RGGI allowances
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	198	707
Accumulated Amortization	[1]	$ 0	$ 613

[1] Includes $370 million and $209 million of renewable energy credits consumed and retired in 2024 and 2023, respectively. In addition, balances at December 31, 2023 includes $613 million of RGGI allowances consumed, including $198 million purchased and consumed in 2023, all of which were retired in 2024. All amounts for renewable energy credits and RGGI allowances were deferred to regulatory assets upon consumption.