Income Taxes - Reconciliation to Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
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	(5.40%)	1.10%	9.90%	2.00%
Plant basis differences	(3.30%)	(4.00%)	(3.50%)	(3.60%)
Excess deferred tax amortization	(10.50%)	(13.40%)	(11.00%)	(12.50%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.40%)	(1.00%)	0.80%	(0.50%)
Other	7.70%	(2.70%)	4.70%	(1.60%)
Effective income tax rate	9.00%	0.90%	21.80%	4.70%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount			$ 67
Income Tax Credits and Adjustments			15
Total transaction costs relating to the Separation			19
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ 48		48
Federal and State
Increase (decrease) due to:
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount			67
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			40
Income Tax Credits and Adjustments			17
Current State and Local Tax Expense (Benefit)	43		43
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ 5		$ 4
Commonwealth Edison Co [Member]
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	7.90%	8.00%	7.90%	7.40%
Plant basis differences	(0.50%)	(0.70%)	(0.50%)	(0.60%)
Excess deferred tax amortization	(5.50%)	(7.00%)	(5.80%)	(7.00%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.30%)	(0.80%)	(0.30%)	(0.50%)
Other	0.00%	(1.10%)	0.10%	(2.30%)
Effective income tax rate	22.50%	19.30%	22.30%	17.90%
PECO Energy Co [Member]
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	(0.60%)	(2.90%)	(0.30%)	(2.10%)
Plant basis differences	(11.00%)	(12.50%)	(11.20%)	(11.30%)
Excess deferred tax amortization	(3.10%)	(3.30%)	(3.20%)	(3.30%)
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	0.00%	0.00%	0.00%	0.00%
Other	0.00%	(0.40%)	0.30%	(0.10%)
Effective income tax rate	6.30%	1.90%	6.60%	4.20%
Baltimore Gas and Electric Company [Member]
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	2.10%	(12.50%)	2.30%	(10.50%)
Plant basis differences	(1.30%)	(2.30%)	(1.00%)	(1.60%)
Excess deferred tax amortization	(19.00%)	(17.50%)	(17.80%)	(15.90%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(1.50%)	(3.60%)	(0.60%)	(0.90%)
Other	1.40%	(6.60%)	0.30%	(1.00%)
Effective income tax rate	2.60%	(21.60%)	4.10%	(9.00%)
Pepco Holdings LLC [Member]
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	1.50%	2.40%	2.80%	4.20%
Plant basis differences	(1.70%)	(1.10%)	(1.70%)	(1.30%)
Excess deferred tax amortization	(19.20%)	(22.30%)	(18.30%)	(20.80%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.40%)	(0.80%)	(0.40%)	(0.50%)
Other	(0.10%)	(1.30%)	0.10%	(0.70%)
Effective income tax rate	1.00%	(2.20%)	3.40%	1.80%
Potomac Electric Power Company [Member]
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	(3.40%)	(2.10%)	(3.80%)	1.50%
Plant basis differences	(2.40%)	(1.50%)	(2.50%)	(1.80%)
Excess deferred tax amortization	(15.70%)	(19.00%)	(16.30%)	(17.20%)
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.40%)	(0.70%)	(0.40%)	(0.50%)
Other	(0.50%)	(1.90%)	(0.70%)	(0.80%)
Effective income tax rate	(1.40%)	(4.20%)	(2.70%)	2.20%
Delmarva Power and Light Company [Member]
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	7.20%	7.00%	6.50%	6.60%
Plant basis differences	(0.70%)	(0.70%)	(0.70%)	(0.70%)
Excess deferred tax amortization	(20.00%)	(21.90%)	(19.50%)	(19.70%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)	(0.20%)	(0.20%)	(0.20%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.40%)	(0.90%)	(0.30%)	(0.40%)
Other	1.80%	(1.10%)	0.40%	(0.10%)
Effective income tax rate	8.70%	3.20%	7.20%	6.50%
Atlantic City Electric Company [Member]
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	6.70%	8.10%	6.70%	7.80%
Plant basis differences	(1.00%)	(0.60%)	(1.20%)	(0.70%)
Excess deferred tax amortization	(24.50%)	(28.20%)	(22.90%)	(28.30%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)	(0.20%)	(0.20%)	(0.20%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.40%)	(0.60%)	(0.30%)	(0.50%)
Other	(1.60%)	(2.30%)	(0.50%)	(1.10%)
Effective income tax rate	0.00%	(2.80%)	2.60%	(2.00%)