Significant Accounting Policies (Narrative) (Detail) - USD ($) $ in Millions	Jan. 01, 2021	Dec. 31, 2023	Dec. 31, 2022
Significant Accounting Policies [Line Items]
Increase (decrease) in retained earnings	$ 660
Cumulative increase to noncontrolling interests	223
Accrued unbilled revenue		$ 1,000	$ 1,100
Current Assets Held for Sale | Held for Sale
Significant Accounting Policies [Line Items]
Accrued unbilled revenue		284	324
Virginia Electric and Power Company
Significant Accounting Policies [Line Items]
Increase (decrease) in retained earnings	$ 143
Accrued unbilled revenue		$ 550	$ 620
Four Brothers And Three Cedars | Dominion Energy Midstream Partners, LP | Terra Nova Renewable Partners | Nonregulated Solar Projects
Significant Accounting Policies [Line Items]
Percentage of equity interest sold to noncontrolling interest owners		33.00%