Leases (Cash Paid for Amounts Included in Measurement of Lease Liabilities) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Lessee Lease Disclosure [Line Items]
Operating cash flows for finance leases	$ 14	$ 13	$ 3
Operating cash flows for operating leases	106	105	82
Financing cash flows for finance leases	50	47	32
Virginia Electric and Power Company
Lessee Lease Disclosure [Line Items]
Operating cash flows for finance leases	5	4	3
Operating cash flows for operating leases	74	64	50
Financing cash flows for finance leases	$ 23	$ 19	$ 12