Commitments and Contingencies - Litigation and Regulatory Matters (Details)			1 Months Ended	3 Months Ended	9 Months Ended
	Nov. 19, 2013 USD ($)	Jul. 11, 2011 Customer	Jan. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) Open_claim claimant	Sep. 30, 2015 USD ($) Open_claim Customer claimant	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 05, 2013 Customer
Telephone Consumer Protection Act Lawsuit [Abstract]
Litigation Settlement, Amount			$ 14,000,000
Exelon Generation Co L L C [Member]
Loss Contingency, Estimate [Abstract]
Loss Contingency, Estimate of Possible Loss							$ 105,000,000
Loss Contingency, Pending Claims, Number | Open_claim				217	217
Exelon Generation Co L L C [Member] | Asbestos Issue [Member]
Loss Contingency, Estimate [Abstract]
Loss Contingency, Estimate of Possible Loss				$ 95,000,000	$ 95,000,000
Estimated Litigation Liability, Noncurrent				75,000,000	75,000,000
Exelon Generation Co L L C [Member] | Pending Litigation [Member] | Asbestos Issue [Member]
Loss Contingency, Estimate [Abstract]
Loss Contingency, Estimate of Possible Loss				20,000,000	$ 20,000,000	$ 100,000,000
Commonwealth Edison Co [Member]
Continuous Power Interruption [Abstract]
Minimum number of customers ComEd can be held liable to for power interruption | Customer					30,000
Number of customers affected by a major storm | Customer		900,000
Number of customers proposed by the ICC that ComEd should not be granted a waiver under Continuous Power Interruption | Customer								34,559
Commonwealth Edison Co [Member] | Settled Litigation [Member] | Telephone Consumer Protection Act Lawsuit [Member]
Telephone Consumer Protection Act Lawsuit [Abstract]
Litigation Settlement, Amount				$ 5,000,000
Loss Contingency, Estimate [Abstract]
Loss Contingency, Number of Plaintiffs | claimant				1,200,000
Commonwealth Edison Co [Member] | Maximum [Member] | Pending Litigation [Member] | Telephone Consumer Protection Act Lawsuit [Member]
Telephone Consumer Protection Act Lawsuit [Abstract]
Loss Contingency, Damages Sought, Value	$ 1,500
Commonwealth Edison Co [Member] | Minimum [Member] | Pending Litigation [Member] | Telephone Consumer Protection Act Lawsuit [Member]
Telephone Consumer Protection Act Lawsuit [Abstract]
Loss Contingency, Damages Sought, Value	$ 500
Baltimore Gas and Electric Company [Member]
Loss Contingency, Estimate [Abstract]
Loss Contingency, Estimate of Possible Loss				$ 1,700,000	$ 1,700,000
Baltimore Gas and Electric Company [Member] | Pending Litigation [Member] | Asbestos Issue [Member]
Loss Contingency, Estimate [Abstract]
Loss Contingency, Number of Plaintiffs | claimant					468