Goodwill and Intangible Assets (Components of Intangible Assets) (Detail) - Software, Licenses and Other - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	$ 2,185	$ 1,723
Accumulated Amortization	[1]	1,240	927
Virginia Electric and Power Company
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	1,509	1,113
Accumulated Amortization	[1]	$ 856	$ 577

[1] Includes $198 million and $253 million of RGGI allowances purchased and consumed in 2023 and 2022, respectively, with deferral to a regulatory asset.