Nuclear Decommissioning (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Fund Investments	$ 10,607	$ 10,537
Decommissioning Liability, Noncurrent	135	155
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Fund Investments	10,607	10,537
Decommissioning Liability, Noncurrent	135	$ 155
Nuclear Plant [Member] | Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 88