Income Taxes - Reconciliation to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
U.S. Federal statutory rate	35.00%	35.00%	35.00%	[1]
State income taxes, net of Federal income tax benefit	3.70%	1.30%	4.80%	[1]
Qualified nuclear decommissioning trust fund loss	0.40%	(2.40%)	(3.70%)	[1]
Domestic production activities deduction	(0.70%)	(2.00%)	(0.00%)
Health care reform legislation	(0.00%)	(0.10%)	(0.10%)	[1]
Amortization of investment tax credit, including deferred taxes on basis difference	(0.90%)	(1.10%)	(1.90%)	[1]
Plant basis differences	(1.50%)	(1.90%)	(2.10%)	[1]
Statute of limitations expiration	(1.40%)	(2.60%)	(0.10%)
Production tax credits and other credits	(1.90%)	(2.40%)	(1.60%)	[1]
Non-controlling interest	0.30%	(1.80%)
Other	(0.00%)	0.20%	0.30%
Effective income tax rate	32.20%	26.80%	37.60%	[1]
Exelon Generation Co L L C [Member]
Income Taxes [Line Items]
U.S. Federal statutory rate	35.00%	35.00%	35.00%	[1]
State income taxes, net of Federal income tax benefit	1.00%	(1.90%)	1.80%	[1]
Qualified nuclear decommissioning trust fund loss	0.80%	(4.80%)	(6.10%)	[1]
Domestic production activities deduction	(1.30%)	(4.10%)	(0.00%)
Health care reform legislation	(0.00%)	(0.00%)	(0.00%)	[1]
Amortization of investment tax credit, including deferred taxes on basis difference	(1.50%)	(2.00%)	(3.00%)	[1]
Plant basis differences	(0.00%)	(0.00%)	(3.40%)	[1]
Statute of limitations expiration	(2.40%)	(5.30%)	(0.20%)
Production tax credits and other credits	(3.40%)	(4.80%)	(0.00%)	[1]
Non-controlling interest	0.50%	(3.70%)
Other	(0.00%)	1.10%	(0.40%)
Effective income tax rate	27.10%	16.90%	36.70%	[1]
Commonwealth Edison Co [Member]
Income Taxes [Line Items]
U.S. Federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit	4.90%	4.50%	3.40%
Qualified nuclear decommissioning trust fund loss	(0.00%)	(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)	(0.00%)	(0.00%)
Health care reform legislation	(0.00%)	(0.20%)	(0.70%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.30%)	(0.30%)	(0.60%)
Plant basis differences	(0.10%)	(0.10%)	(0.10%)
Statute of limitations expiration	(0.00%)	(0.00%)	(0.00%)
Production tax credits and other credits	(0.00%)	(0.00%)	(0.80%)
Non-controlling interest	0.00%
Other	(0.20%)	(0.30%)	(0.30%)
Effective income tax rate	39.70%	39.60%	37.90%
PECO Energy Co [Member]
Income Taxes [Line Items]
U.S. Federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit	1.00%	(0.10%)	1.60%
Qualified nuclear decommissioning trust fund loss	(0.00%)	(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)	(0.00%)	(0.00%)
Health care reform legislation	(0.00%)	(0.00%)	(0.00%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.10%)	(0.10%)
Plant basis differences	(8.70%)	(10.40%)	(0.00%)
Statute of limitations expiration		(0.00%)	(0.00%)
Production tax credits and other credits	(0.00%)	(0.00%)	(7.10%)
Non-controlling interest	0.00%
Other	(0.20%)	(0.10%)	0.30%
Effective income tax rate	27.40%	24.50%	29.10%
Baltimore Gas and Electric Company [Member]
Income Taxes [Line Items]
U.S. Federal statutory rate	35.00%	35.00%	35.00%	[2]
State income taxes, net of Federal income tax benefit	5.30%	5.00%	4.90%	[2]
Qualified nuclear decommissioning trust fund loss	(0.00%)	(0.00%)	(0.00%)	[2]
Domestic production activities deduction	(0.00%)	(0.00%)	(0.00%)
Health care reform legislation	(0.10%)	(0.20%)	(0.20%)	[2]
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)	(0.30%)	(0.00%)	[2]
Plant basis differences	(0.70%)	0.20%	(0.00%)	[2]
Statute of limitations expiration	(0.00%)	(0.00%)	(0.00%)
Production tax credits and other credits	(0.00%)	(0.00%)	(0.20%)	[2]
Non-controlling interest	0.00%
Other	(0.00%)	0.20%	0.90%
Effective income tax rate	39.60%	39.90%	39.00%	[2]

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