v2.4.0.6
Commitments and Contingencies (Schedules of Future Minimum Rental Payments) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Land and Other Operating Leases [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due $ 300    
Operating Leases, Future Minimum Payments Due, Current 14    
Operating Leases, Future Minimum Payments, Due in Two Years 14    
Operating Leases, Future Minimum Payments, Due in Three Years 14    
Operating Leases, Future Minimum Payments, Due in Four Years 15    
Operating Leases, Future Minimum Payments, Due in Five Years 15    
Operating Leases, Future Minimum Payments, Due Thereafter 228    
Greenleaf [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 10    
KIAC [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 167    
Operating Leases, Future Minimum Payments Due, Current 24    
Operating Leases, Future Minimum Payments, Due in Two Years 24    
Operating Leases, Future Minimum Payments, Due in Three Years 23    
Operating Leases, Future Minimum Payments, Due in Four Years 22    
Operating Leases, Future Minimum Payments, Due in Five Years 22    
Operating Leases, Future Minimum Payments, Due Thereafter 52    
Total Power Plant Leases [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 177    
Operating Leases, Future Minimum Payments Due, Current 31    
Operating Leases, Future Minimum Payments, Due in Two Years 27    
Operating Leases, Future Minimum Payments, Due in Three Years 23    
Operating Leases, Future Minimum Payments, Due in Four Years 22    
Operating Leases, Future Minimum Payments, Due in Five Years 22    
Operating Leases, Future Minimum Payments, Due Thereafter 52    
Operating Leases, Rent Expense, Net 51 53 60
Operting Lease Assets Total [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 477    
Operating Leases, Future Minimum Payments Due, Current 45    
Operating Leases, Future Minimum Payments, Due in Two Years 41    
Operating Leases, Future Minimum Payments, Due in Three Years 37    
Operating Leases, Future Minimum Payments, Due in Four Years 37    
Operating Leases, Future Minimum Payments, Due in Five Years 37    
Operating Leases, Future Minimum Payments, Due Thereafter 280    
Office Equipment [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 91    
Operating Leases, Future Minimum Payments Due, Current 12    
Operating Leases, Future Minimum Payments, Due in Two Years 12    
Operating Leases, Future Minimum Payments, Due in Three Years 12    
Operating Leases, Future Minimum Payments, Due in Four Years 12    
Operating Leases, Future Minimum Payments, Due in Five Years 12    
Operating Leases, Future Minimum Payments, Due Thereafter 31    
Operating Leases, Rent Expense, Net 12 13 12
Greenleaf [Member]
      
Operating Leased Assets [Line Items]      
Guarantee Obligations Balance On First Anniversary 7    
Guarantee Obligations Balance On Second Anniversary 3    
Guarantee Obligations Balance On Third Anniversary 0    
Guarantee Obligations Balance On Fourth Anniversary 0    
Guarantee Obligations Balance On Fifth Anniversary 0    
Guarantee Obligations Due After Five Years $ 0