Significant Accounting Policies (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2022
Change in Depreciation Rates from New Depreciation Study
Significant Accounting Policies [Line Items]
Increase in EPS	$ 0.01
Change in Depreciation Rates from New Depreciation Study | Forecast
Significant Accounting Policies [Line Items]
Increase in EPS		$ 0.05
Virginia Electric and Power Company | Change in Depreciation Rates from New Depreciation Study
Significant Accounting Policies [Line Items]
Increase (decrease) in depreciation expense	$ (15)
Increase (decrease) in depreciation expense, after tax	$ (11)
Virginia Electric and Power Company | Change in Depreciation Rates from New Depreciation Study | Forecast
Significant Accounting Policies [Line Items]
Increase (decrease) in depreciation expense		$ (60)
Increase (decrease) in depreciation expense, after tax		$ (45)
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%