Related-Party Transactions (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Related Party Transaction [Line Items]
Services provided to affiliates		$ 3,486	$ 3,166	$ 7,118	$ 7,049
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Commodity purchases from affiliates		108	103	306	317
Services provided to affiliates	[1]	2,537	2,252	5,026	4,636
Virginia Electric and Power Company | Related Party
Related Party Transaction [Line Items]
Services provided by affiliates	[2]	171	145	326	292
Services provided to affiliates		$ 4	$ 4	$ 8	$ 8

[1] See Note 19 for amounts attributable to affiliates.

[2] Includes capitalized expenditures of $58 million and $46 million for the three months ended June 30, 2024 and 2023, respectively and $111 million and $100 million for the six months ended June 30, 2024 and 2023, respectively.