Income Taxes (Reconciliation of Income Taxes at the U.S. Statutory Federal Income Tax Rate) (Detail)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	3.40%	3.80%
Investment tax credits	(1.30%)	(1.10%)
Production tax credits	(1.00%)	(0.40%)
Reversal of excess deferred income taxes	(2.10%)	(2.00%)
AFUDC - equity	(0.70%)	(0.10%)
Other, net	0.10%	(1.10%)
Effective tax rate	19.40%	20.10%
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%	4.60%
Investment tax credits	(0.70%)	(0.80%)
Production tax credits	(0.90%)	(0.70%)
Reversal of excess deferred income taxes	(1.70%)	(2.70%)
AFUDC - equity	(0.70%)	0.20%
Other, net	0.20%	(0.20%)
Effective tax rate	21.60%	21.40%