Income Taxes (Reconciliation of Income Taxes at the U.S. Statutory Federal Income Tax Rate) (Detail)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.80%	2.80%
Investment tax credits	(3.10%)	(2.40%)
Production tax credits	(6.10%)	(1.80%)
Reversal of excess deferred income taxes	(2.10%)	(3.90%)
Remeasurements and settlements of uncertain tax positions	(4.00%)
AFUDC - equity	(1.00%)	(1.30%)
Absence of tax on noncontrolling interest	(2.20%)
Other, net	0.10%	0.10%
Effective tax rate	7.40%	14.50%
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%	4.40%
Investment tax credits	(0.90%)	(0.70%)
Production tax credits	(4.40%)	(0.90%)
Reversal of excess deferred income taxes	(1.90%)	(1.70%)
AFUDC - equity	(1.10%)	(0.70%)
Absence of tax on noncontrolling interest	(2.50%)
Other, net	0.20%	0.20%
Effective tax rate	14.80%	21.60%