Variable Interest Entities - (Narrative) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Payable to affiliates	[1]	$ 1,732	$ 1,695
Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Payable to affiliates		$ 908	826
Variable Interest Entity Not Primary Beneficiary | Distribution | Atlantic Coast Pipeline | Pipelines | Jointly Owned Natural Gas Pipeline
Variable Interest Entity [Line Items]
Initial membership interest percentage		53.00%
Variable Interest Entity Not Primary Beneficiary | Virginia Electric and Power Company | DES
Variable Interest Entity [Line Items]
Shared Services Purchased		$ 463	396	$ 380
Variable Interest Entity Not Primary Beneficiary | Virginia Electric and Power Company | DES | Related Party
Variable Interest Entity [Line Items]
Payable to affiliates		$ 32	$ 28

[1] See Note 9 for amounts attributable to related parties.