Nuclear Decommissioning (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 54	$ 90
Decommissioning Fund Investments	10,737	10,342
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	54	90
Decommissioning Fund Investments	10,737	$ 10,342
Nuclear Plant [Member] | Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 86