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Derivative Financial Instruments (Commodity Price Risk) (Details)
3 Months Ended 9 Months Ended
Sep. 30, 2013
GWh
Sep. 30, 2012
GWh
Sep. 30, 2013
GWh
Sep. 30, 2012
GWh
Exelon Generation Co L L C [Member]
       
Proprietary Trading Volumes [Abstract]        
Proprietary trading activities volume 2,499 4,352 6,066 9,981
Exelon Generation Co L L C [Member] | Minimum [Member]
       
Percent Of Expected Generation Being Hedged [Abstract]        
Expected generation hedged in next twelve months     97.00%  
Expected generation hedged in year two     84.00%  
Expected generation hedged in year three     48.00%  
Exelon Generation Co L L C [Member] | Maximum [Member]
       
Percent Of Expected Generation Being Hedged [Abstract]        
Expected generation hedged in next twelve months     100.00%  
Expected generation hedged in year two     87.00%  
Expected generation hedged in year three     51.00%  
PECO Energy Co [Member]
       
Percent Of Gas Purchases Being Hedged [Abstract]        
Estimated percentage of natural gas purchases hedged     30.00%  
Baltimore Gas and Electric Company [Member] | Minimum [Member]
       
Percent Of Gas Purchases Being Hedged [Abstract]        
Estimated percentage of natural gas purchases hedged     10.00%  
Baltimore Gas and Electric Company [Member] | Maximum [Member]
       
Percent Of Gas Purchases Being Hedged [Abstract]        
Estimated percentage of natural gas purchases hedged     20.00%