Income Taxes (Reconciliation of Income Taxes at the U.S. Statutory Federal Income Tax Rate) (Detail)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
Recognition of taxes - sale of subsidiary stock	7.30%
State taxes, net of federal benefit	4.70%	2.00%
Investment tax credits	(6.40%)	(5.60%)
Production tax credits	(0.70%)	(0.50%)
Reversal of excess deferred income taxes	(6.10%)	(3.80%)
State legislative change		(1.00%)
Changes in state deferred taxes associated with assets held for sale	0.40%	(0.50%)
AFUDC - equity	(0.60%)	(0.50%)
Absence of tax on noncontrolling interest		(0.20%)
Other, net	(0.40%)	(1.10%)
Effective tax rate	19.20%	9.80%
Virginia Electric and Power Company
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.40%	4.50%
Investment tax credits	(8.90%)	(5.80%)
Production tax credits	(1.00%)	(0.60%)
Reversal of excess deferred income taxes	(3.70%)	(2.20%)
State legislative change		(1.00%)
AFUDC - equity	(0.80%)	(0.50%)
Other, net	0.50%
Effective tax rate	11.50%	15.40%