Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	$ 44	$ 34	$ 47
Operating leases	211	110	49
Virginia Electric and Power Company
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	30	26	37
Operating leases	$ 173	$ 90	$ 42