Income Taxes (Reconciliation of Income Taxes at the U.S. Statutory Federal Income Tax Rate) (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%	21.00%
Increases (reductions) resulting from:
Recognition of taxes - sale of subsidiary stock	0.00%	17.00%	0.00%
State taxes, net of federal benefit	4.10%	11.30%	1.10%
Investment tax credits	(1.00%)	(7.70%)	(23.60%)
Production tax credits	(0.60%)	(2.70%)	(0.70%)
Valuation allowances	0.00%	0.00%	0.20%
Reversal of excess deferred income taxes	(2.60%)	(15.30%)	(3.30%)
State legislative change	(0.10%)	(0.10%)	(1.10%)
AFUDC - equity	0.00%	(1.10%)	(0.60%)
Changes in state deferred taxes associated with assets held for sale	1.10%	0.90%	0.00%
Absence of tax on noncontrolling interest	0.00%	0.00%	(0.20%)
Settlements of uncertain tax positions	(0.40%)	0.00%	(2.00%)
Employee stock ownership plan deduction	(0.30%)	(1.50%)	(0.50%)
Other, net	(0.20%)	(0.90%)	0.00%
Effective tax rate	21.00%	20.90%	(9.70%)
Virginia Electric and Power Company
Effective Income Tax Computation [Line Items]
U.S. statutory rate	21.00%	21.00%	21.00%
Increases (reductions) resulting from:
Recognition of taxes - privatization intercompany gain	0.00%	2.40%	0.00%
State taxes, net of federal benefit	4.70%	4.60%	4.60%
Investment tax credits	(0.80%)	(2.00%)	(0.80%)
Production tax credits	(0.80%)	(1.00%)	(0.60%)
Valuation allowances	0.00%	0.00%	0.00%
Reversal of excess deferred income taxes	(2.60%)	(3.80%)	(2.10%)
State legislative change	0.00%	0.00%	(0.70%)
AFUDC - equity	0.00%	(0.40%)	(0.50%)
Settlements of uncertain tax positions	0.00%	0.00%	0.00%
Other, net	(0.40%)	0.10%	0.30%
Effective tax rate	21.10%	20.90%	21.20%