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, 2011
Dec. 31, 2010
Dec. 31, 2009
Land and Other Operating Leases [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due, Current $ 12    
Operating Leases, Future Minimum Payments, Due in Two Years 11    
Operating Leases, Future Minimum Payments, Due in Three Years 11    
Operating Leases, Future Minimum Payments, Due in Four Years 14    
Operating Leases, Future Minimum Payments, Due in Five Years 14    
Operating Leases, Future Minimum Payments, Due Thereafter 431    
Operating Leases, Future Minimum Payments Due 493    
Greenleaf [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due 17    
KIAC [Member]
      
Operating Leased Assets [Line Items]      
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 24    
Operating Leases, Future Minimum Payments, Due in Four Years 23    
Operating Leases, Future Minimum Payments, Due in Five Years 22    
Operating Leases, Future Minimum Payments, Due Thereafter 74    
Operating Leases, Future Minimum Payments Due 191    
Total Power Plant Leases [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due, Current 31    
Operating Leases, Future Minimum Payments, Due in Two Years 31    
Operating Leases, Future Minimum Payments, Due in Three Years 27    
Operating Leases, Future Minimum Payments, Due in Four Years 23    
Operating Leases, Future Minimum Payments, Due in Five Years 22    
Operating Leases, Future Minimum Payments, Due Thereafter 74    
Operating Leases, Future Minimum Payments Due 208    
Operating Leases, Rent Expense, Net 53 60 60
Operting Lease Assets Total [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due, Current 43    
Operating Leases, Future Minimum Payments, Due in Two Years 42    
Operating Leases, Future Minimum Payments, Due in Three Years 38    
Operating Leases, Future Minimum Payments, Due in Four Years 37    
Operating Leases, Future Minimum Payments, Due in Five Years 36    
Operating Leases, Future Minimum Payments, Due Thereafter 505    
Operating Leases, Future Minimum Payments Due 701    
Office Equipment [Member]
      
Operating Leased Assets [Line Items]      
Operating Leases, Future Minimum Payments Due, Current 13    
Operating Leases, Future Minimum Payments, Due in Two Years 12    
Operating Leases, Future Minimum Payments, Due in Three Years 10    
Operating Leases, Future Minimum Payments, Due in Four Years 10    
Operating Leases, Future Minimum Payments, Due in Five Years 9    
Operating Leases, Future Minimum Payments, Due Thereafter 32    
Operating Leases, Future Minimum Payments Due 86    
Operating Leases, Rent Expense, Net 13 12 12
Greenleaf [Member]
      
Operating Leased Assets [Line Items]      
Guarantee Obligations Balance On First Anniversary 7 [1]    
Guarantee Obligations Balance On Second Anniversary 7 [1]    
Guarantee Obligations Balance On Third Anniversary 3 [1]    
Guarantee Obligations Balance On Fourth Anniversary 0 [1]    
Guarantee Obligations Balance On Fifth Anniversary 0 [1]    
Guarantee Obligations Due After Five Years $ 0 [1]    
[1] These are contingent off balance sheet obligations.