Income Taxes - Reconciliation to Effective Tax Rate (Details)		3 Months Ended
	Mar. 31, 2016	Mar. 31, 2016	Mar. 23, 2016	Mar. 31, 2015
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		(1.10%)		2.60%
Qualified nuclear decommissioning trust fund income		5.60%		1.90%
Domestic production activities deduction		0.00%		(2.20%)
Health care reform legislation		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		(1.60%)		(0.90%)
Plant basis differences		(5.50%)		(1.30%)
Production tax credits and other credits		5.10%		1.80%
Non-controlling interest		0.50%		(0.70%)
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent		33.60%
Other		(2.00%)		0.40%
Effective income tax rate		59.40%		33.00%
Exelon Generation Co L L C [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		3.70%		2.70%
Qualified nuclear decommissioning trust fund income		4.20%		3.00%
Domestic production activities deduction		0.00%		(3.40%)
Health care reform legislation		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		(1.00%)		(1.40%)
Plant basis differences		0.00%		0.00%
Production tax credits and other credits		3.90%		2.80%
Non-controlling interest		0.30%		(1.10%)
Other		(1.60%)		(0.20%)
Effective income tax rate		36.70%		31.80%
Commonwealth Edison Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		5.10%		5.00%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		(0.30%)		(0.30%)
Plant basis differences		(0.10%)		(0.30%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Other		0.40%		0.20%
Effective income tax rate		40.10%		39.60%
PECO Energy Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		1.00%		1.20%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		(0.10%)		(0.10%)
Plant basis differences		(9.30%)		(6.70%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Other		(0.90%)		0.00%
Effective income tax rate		25.70%		29.40%
Baltimore Gas and Electric Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		5.20%		5.30%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.00%		0.20%
Amortization of investment tax credit, including deferred taxes on basis difference		(0.10%)		0.00%
Plant basis differences		(0.60%)		(0.30%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Other		0.00%		0.20%
Effective income tax rate		39.50%		40.40%
Pepco Holdings, LLC [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)				7.20%
Amortization of investment tax credit, including deferred taxes on basis difference				(0.50%)
Plant basis differences				(4.90%)
Other				(0.70%)
Effective income tax rate				36.10%
Pepco Holdings, LLC [Member] | Predecessor [Member]
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)			11.90%
Qualified nuclear decommissioning trust fund income			0.00%
Domestic production activities deduction			0.00%
Health care reform legislation			(0.90%)
Amortization of investment tax credit, including deferred taxes on basis difference			(13.50%)
Production tax credits and other credits			(0.00%)
Non-controlling interest			0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent			11.10%
Other			3.60%
Effective income tax rate			47.20%
Pepco Holdings, LLC [Member] | Successor [Member]
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)	5.40%
Qualified nuclear decommissioning trust fund income	0.00%
Domestic production activities deduction	0.00%
Health care reform legislation	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	0.00%
Production tax credits and other credits	(0.00%)
Non-controlling interest	0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent	(15.10%)
Other	0.20%
Effective income tax rate	25.50%
Potomac Electric Power Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate				35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		(2.50%)		5.30%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.00%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		2.80%		(0.10%)
Plant basis differences				(8.50%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent		(16.50%)
Other		0.00%		(0.10%)
Effective income tax rate		18.80%		31.60%
Delmarva Power and Light Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		(2.70%)		5.70%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.20%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		0.60%		(0.20%)
Plant basis differences				(0.90%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent		(22.10%)
Other		0.10%		0.00%
Effective income tax rate		11.10%		39.60%
Atlantic City Electric Company [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate		35.00%		35.00%
Increase (decrease) due to:
State income taxes, net of Federal income tax benefit (b)		5.90%		5.90%
Qualified nuclear decommissioning trust fund income		0.00%		0.00%
Domestic production activities deduction		0.00%
Health care reform legislation		0.10%		0.00%
Amortization of investment tax credit, including deferred taxes on basis difference		0.70%		(1.40%)
Plant basis differences				(2.80%)
Production tax credits and other credits		(0.00%)		(0.00%)
Non-controlling interest		0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent		(17.00%)
Other		0.10%		(1.00%)
Effective income tax rate		24.80%		35.70%
Atlantic City Electric Company [Member] | Predecessor [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate			35.00%
Atlantic City Electric Company [Member] | Successor [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal statutory rate	35.00%