Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Parenthetical) (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022		Mar. 31, 2022	Dec. 31, 2021
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	$ 1,792	$ 153	[1]
Current Assets Held for Sale
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	$ 0	$ 0		$ 2	$ 0

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