Income Taxes - Reconciliation to Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2023	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			3.90%	8.80%	5.00%
Plant basis differences			(3.90%)	(4.10%)	(5.40%)
Excess deferred tax amortization			(6.60%)	(11.80%)	(17.20%)
Amortization of investment tax credit, including deferred taxes on basis difference			(0.10%)	(0.10%)	(0.10%)
Production tax credits and other credits			(0.60%)	0.10%	(0.70%)
Other			0.10%	0.60%	(0.30%)
Effective income tax rate			13.80%	14.50%	2.30%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	$ 54	$ 54		$ 43
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount				67
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				40
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount				9
Income Tax Credits and Adjustments				15
Total transaction costs relating to the Separation				12
EXCFederal And State
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		40
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount				$ 11
Income Tax Credits and Adjustments		$ 17
Commonwealth Edison Co
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			7.90%	8.00%	7.80%
Plant basis differences			(0.50%)	(0.60%)	(0.80%)
Excess deferred tax amortization			(5.50%)	(5.60%)	(7.60%)
Amortization of investment tax credit, including deferred taxes on basis difference			(0.10%)	(0.10%)	0.10%
Production tax credits and other credits			(0.60%)	(0.30%)	(0.50%)
Other			0.20%	0.00%	(1.00%)
Effective income tax rate			22.40%	22.40%	18.80%
PECO Energy Co
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			(1.00%)	5.80%	(1.40%)
Plant basis differences			(14.40%)	(11.90%)	(13.60%)
Excess deferred tax amortization			(2.40%)	(3.00%)	(3.80%)
Amortization of investment tax credit, including deferred taxes on basis difference			0.00%	0.00%	0.00%
Production tax credits and other credits			0.00%	0.00%	0.00%
Other			0.20%	0.20%	0.10%
Effective income tax rate			3.40%	12.10%	2.30%
Increase (Decrease) in Income Taxes				$ 38
Baltimore Gas and Electric Company
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			6.40%	2.60%	(10.80%)
Plant basis differences			(0.90%)	(1.00%)	(1.70%)
Excess deferred tax amortization			(4.60%)	(19.80%)	(16.30%)
Amortization of investment tax credit, including deferred taxes on basis difference			0.00%	(0.10%)	0.10%
Production tax credits and other credits			(0.60%)	(0.70%)	(0.90%)
Other			0.20%	0.10%	(0.60%)
Effective income tax rate			21.50%	2.10%	(9.40%)
Pepco Holdings LLC
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			5.90%	2.10%	10.10%
Plant basis differences			(1.40%)	(1.70%)	(1.10%)
Excess deferred tax amortization			(8.60%)	(19.50%)	(22.40%)
Amortization of investment tax credit, including deferred taxes on basis difference			(0.10%)	(0.10%)	0.10%
Production tax credits and other credits			(0.60%)	(0.70%)	(0.50%)
Other			0.20%	0.40%	0.00%
Effective income tax rate			16.40%	1.50%	7.00%
Potomac Electric Power Company
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			5.50%	(4.10%)	2.70%
Plant basis differences			(2.20%)	(2.70%)	(1.60%)
Excess deferred tax amortization			(9.60%)	(16.80%)	(16.40%)
Amortization of investment tax credit, including deferred taxes on basis difference			0.00%	0.00%	0.00%
Production tax credits and other credits			(0.70%)	(0.70%)	(0.50%)
Other			0.30%	0.30%	(0.40%)
Effective income tax rate			14.30%	(3.00%)	4.80%
Delmarva Power & Light Company
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			6.10%	6.50%	25.00%
Plant basis differences			(0.70%)	(0.70%)	(0.80%)
Excess deferred tax amortization			(9.40%)	(18.40%)	(20.00%)
Amortization of investment tax credit, including deferred taxes on basis difference			(0.10%)	(0.20%)	0.20%
Production tax credits and other credits			(0.40%)	(0.60%)	(0.40%)
Other			0.00%	0.10%	0.10%
Effective income tax rate			16.50%	7.70%	24.70%
Valuation allowance on state tax attributes (net of federal taxes)					$ 31
Atlantic City Electric Company
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Line Items]
U.S. Federal statutory rate			21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit			7.10%	6.90%	7.40%
Plant basis differences			(0.40%)	(0.70%)	(0.20%)
Excess deferred tax amortization			(4.20%)	(24.50%)	(37.10%)
Amortization of investment tax credit, including deferred taxes on basis difference			(0.20%)	(0.20%)	0.20%
Production tax credits and other credits			(0.50%)	(0.50%)	(0.50%)
Other			0.30%	0.00%	(0.20%)
Effective income tax rate			23.10%	2.00%	(9.80%)