XML 57 R38.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Commitments and Contingencies (Tables)
 6 Months Ended
Jun. 30, 2011
Commitments And Contingencies Tables Disclosure [Line Items]  
Accrued environmental liabilities [Text Block]
 June 30, 2011Total Environmental Investigation and Remediation Reserve  Portion of Total Related to MGP Investigation and Remediation  
 Exelon$181 $156 
 Generation 16  0 
 ComEd 118  112 
 PECO 47  44 
        
 December 31, 2010Total Environmental Investigation and Remediation Reserve  Portion of Total Related to MGP Investigation and Remediation  
 Exelon$179 $156 
 Generation 15  0 
 ComEd 120  114 
 PECO 44  42