Income Taxes - Reconciliation to Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(2.70%)	9.00%	2.80%	9.50%
Plant basis differences	(4.40%)	(5.30%)	(4.30%)	(4.20%)
Excess deferred tax amortization	(6.40%)	(11.60%)	(6.60%)	(11.30%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Tax credits	(0.50%)	(0.60%)	(0.50%)	0.30%
Other	1.80%	(0.40%)	1.50%	2.80%
Effective income tax rate	8.70%	12.00%	13.80%	18.00%
Current state and local tax expense (benefit)				$ 43
Effective income tax rate reconciliation, other adjustments, amount			$ 40
Income tax credits and adjustments				15
Total transaction costs relating to the Separation				19
Increase (decrease) in income taxes				38
Federal and State
Increase (decrease) due to:
Effective income tax rate reconciliation, state and local income taxes, amount	$ (54)		$ (54)	67
Valuation allowance, deferred tax asset, increase (decrease), amount				40
Indemnification Agreement
Increase (decrease) due to:
Effective income tax rate reconciliation, other adjustments, amount				$ 4
Commonwealth Edison Co
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	7.80%	8.00%	7.80%	7.90%
Plant basis differences	(0.40%)	(0.40%)	(0.40%)	(0.50%)
Excess deferred tax amortization	(5.30%)	(5.60%)	(5.50%)	(5.70%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Tax credits	(1.20%)	(0.40%)	(0.70%)	(0.30%)
Other	0.20%	(0.10%)	0.10%	0.00%
Effective income tax rate	22.00%	22.40%	22.20%	22.30%
PECO Energy Co
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	(1.20%)	20.70%	(1.30%)	6.60%
Plant basis differences	(15.60%)	(14.20%)	(15.50%)	(12.20%)
Excess deferred tax amortization	(2.40%)	(3.20%)	(2.40%)	(3.20%)
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	0.00%	0.00%	0.00%
Tax credits	0.00%	0.00%	0.00%	0.00%
Other	0.20%	0.30%	0.10%	0.20%
Effective income tax rate	2.00%	24.60%	1.90%	12.40%
Baltimore Gas and Electric Company
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	6.60%	6.80%	6.50%	2.80%
Plant basis differences	(0.20%)	(2.60%)	(0.50%)	(1.10%)
Excess deferred tax amortization	(5.40%)	(47.30%)	(5.40%)	(20.70%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.20%)	(0.10%)	(0.10%)
Tax credits	(2.00%)	(1.90%)	(0.70%)	(0.70%)
Other	(0.30%)	(2.70%)	0.20%	(0.10%)
Effective income tax rate	19.60%	(26.90%)	21.00%	1.10%
Pepco Holdings LLC
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	6.20%	1.40%	6.10%	2.00%
Plant basis differences	(1.50%)	(1.70%)	(1.60%)	(1.70%)
Excess deferred tax amortization	(8.00%)	(19.30%)	(7.70%)	(18.80%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Tax credits	(0.50%)	(0.90%)	(0.60%)	(0.70%)
Other	0.30%	0.30%	0.30%	0.20%
Effective income tax rate	17.40%	0.70%	17.40%	1.90%
Potomac Electric Power Company
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	5.50%	(2.70%)	5.50%	(3.20%)
Plant basis differences	(2.40%)	(2.30%)	(2.50%)	(2.40%)
Excess deferred tax amortization	(9.20%)	(14.60%)	(9.20%)	(15.40%)
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	0.00%	0.00%	0.00%
Tax credits	(0.60%)	(0.80%)	(0.70%)	(0.60%)
Other	0.60%	0.10%	0.60%	(0.20%)
Effective income tax rate	14.90%	0.70%	14.70%	(0.80%)
Delmarva Power and Light Company
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	6.10%	6.50%	6.20%	6.50%
Plant basis differences	(0.90%)	(0.80%)	(1.00%)	(0.70%)
Excess deferred tax amortization	(10.00%)	(21.70%)	(9.40%)	(20.40%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.20%)	(0.10%)	(0.20%)
Tax credits	(0.40%)	(1.30%)	(0.40%)	(0.70%)
Other	0.00%	0.20%	0.00%	0.30%
Effective income tax rate	15.70%	3.70%	16.30%	5.80%
Atlantic City Electric Company
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	21.00%	21.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit	7.00%	7.00%	6.90%	6.90%
Plant basis differences	(0.50%)	(1.00%)	(0.50%)	(1.10%)
Excess deferred tax amortization	(3.10%)	(25.50%)	(2.60%)	(24.70%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.20%)	(0.10%)	(0.20%)
Tax credits	(0.30%)	(0.70%)	(0.30%)	(0.60%)
Other	0.50%	0.50%	0.30%	0.20%
Effective income tax rate	24.50%	1.10%	24.70%	1.50%