Commitments and Contingencies - Litigation and Regulatory Matters (Details) $ in Millions	Mar. 31, 2016 USD ($) claimant Open_claim	Dec. 31, 2015 USD ($)
Exelon Generation Co L L C [Member]
Asbestos Loss Contingency [Abstract]
Asbestos liability reserve	$ 21	$ 0
Asbestos liability reserve related to open claims	$ 0
Open asbestos liability claims | Open_claim	72,000,000
Asbestos liability reserve related to anticipated claims	$ 95
Telephone Consumer Protection Act Lawsuit [Abstract]
Loss Contingency Accrual	$ 44
Baltimore Gas and Electric Company [Member]
Asbestos Loss Contingency [Abstract]
Number of claimants | claimant	93,000,000