Quarterly Financial Data (Unaudited) (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Quarterly Financial Information Disclosure [Line Items]
Gain on sale of Dominion Energy's noncontrolling interest in cove point		$ 348
Charges reflecting the recognition of deferred taxes		$ 939
Impairment charge associated with the East Ohio and Questar Gas Transactions, after-tax	$ 323
Charges associated with impairment of nonregulated solar generation facilities after tax			$ 633
Loss associated with sale of Kewaunee, after tax				$ 513
Charge in connection with comprehensive settlement agreement for fuel expenses, after-tax				142
Charge for RGGI compliance cost, after tax				134
Virginia Electric and Power Company
Quarterly Financial Information Disclosure [Line Items]
Charge in connection with comprehensive settlement agreement for fuel expenses, after-tax				142
Charge for RGGI compliance cost, after tax				$ 134