Goodwill and Intangible Assets (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Amortization expense for intangible assets	$ 160	$ 103	$ 70
Acquisition of intangible assets	$ 642
Weighted-average amortization period (years)	6 years
Virginia Electric and Power Company
Goodwill [Line Items]
Amortization expense for intangible assets	$ 123	$ 67	$ 31
Acquisition of intangible assets	$ 583
Weighted-average amortization period (years)	5 years