Nuclear Decommissioning (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Fund Investments	$ 10,526	$ 10,342
Decommissioning Liability, Noncurrent	72	90
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Fund Investments	10,526	10,342
Decommissioning Liability, Noncurrent	71	$ 90
Nuclear Plant [Member] | Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 85