Investments (Selected Information Regarding Equity and Fixed Income Securities) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales		$ 3,072	$ 2,966	$ 3,282
Realized gains	[1]	106	92	143
Realized losses	[1]	128	169	296
Virginia Electric and Power Company
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales		1,925	1,876	1,538
Realized gains	[1]	67	50	48
Realized losses	[1]	$ 88	$ 99	$ 107

[1] Includes realized gains and losses recorded to the nuclear decommissioning trust regulatory liability as discussed in Note 2.