Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Basis of Presentation - Narrative (Details) (Exelon Corporate [Member])	Dec. 31, 2014
Exelon Generation Co L L C [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	100.00%
Commonwealth Edison Co [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	99.00%
Baltimore Gas and Electric Company [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	100.00%
Baltimore Gas and Electric Company [Member] | Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	0.00%
PECO Energy Co [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	100.00%
PECO Energy Co [Member] | Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (more than 99% for ComEd)	0.00%