Variable Interest Entities - (Narrative) (Detail) - Virginia Electric and Power Company - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Variable Interest Entity [Line Items]
Payables to affiliates	$ 203		$ 255	[1]
Variable Interest Entity, Not Primary Beneficiary | DES
Variable Interest Entity [Line Items]
Shared Services Purchased	113	$ 98
Payables to affiliates	$ 28		$ 28

[1] Virginia Power’s Consolidated Balance Sheet at December 31, 2022 has been derived from the audited Consolidated Balance Sheet at that date.