Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	$ 11	$ 26
Operating leases	57	135
Virginia Electric and Power Company
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	9	22
Operating leases	$ 41	$ 120