Commitments and Contingencies - Contingencies Narrative (Details) - Jun. 30, 2015 $ in Millions		USD ($) reactor
Commitments And Contingencies Additional Narrative Information [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 10,509.0
Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Total of U.S. licensed nuclear reactors | reactor		102
Nuclear financial protection pool value		$ 375.0
Maximum liability per nuclear incident		13,400.0
Guarantor Obligations, Maximum Exposure, Undiscounted		7,674.0
Funds available for claim		12,900.0
Recovery of Direct Costs		3,200.0
Nuclear Insurance Premiums [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Maximum assessment mandated by Price-Anderson Act per nuclear reactor for a nuclear incident		2,700.0
Guarantor Obligations, Maximum Exposure, Undiscounted	[1]	$ 3,057.0
Nuclear Insurance Premiums [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Nuclear Insurance Financial Protection Pool Surcharge On Nuclear Incident Assessment		5.00%
Maximum assessment mandated by Price-Anderson Act per nuclear reactor for a nuclear incident		$ 127.3
Maximum liability per nuclear incident		19.0
Guarantor Obligations, Maximum Exposure, Undiscounted	[1]	$ 3,057.0

[1] Represents the maximum amount that Generation would be required to pay for retrospective premiums in the event of nuclear disaster at any domestic site, including CENG sites, under the Secondary Financial Protection pool as required under the Price-Anderson Act as well as the current aggregate annual retrospective premium obligation that could be imposed by NEIL. See the Nuclear Insurance section within this note for additional details on Generation’s nuclear insurance premiums.