v2.4.0.6
Debt (Details 4) (USD $)
Dec. 31, 2011
Dec. 31, 2010
Schedule of Future Minimum Lease Payments for Capital Leases [Line Items]    
Power generation capacity 11,391 13,656
Maximum Remaining Lease Term 37  
Minimum Lease Payments, Sale Leaseback Transactions [Abstract]    
Minimum Lease Payments, Sale Leaseback Transactions, within One Year $ 41,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years 38,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions, within Three Years 26,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions, within Four Years 25,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions, within Five Years 25,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions, Thereafter 143,000,000 [1]  
Minimum Lease Payments, Sale Leaseback Transactions 298,000,000 [1]  
Interest Portion of Minimum Lease Payments, Sale Leaseback Transactions 110,000,000 [1]  
Present Value of Future Minimum Lease Payments, Sale Leaseback Transactions 188,000,000 [1]  
Capital Leases, Future Minimum Payments Due [Abstract]    
Capital Leases, Future Minimum Payments Due, Current 40,000,000  
Capital Leases, Future Minimum Payments Due in Two Years 38,000,000  
Capital Leases, Future Minimum Payments Due in Three Years 39,000,000  
Capital Leases, Future Minimum Payments Due in Four Years 37,000,000  
Capital Leases, Future Minimum Payments Due in Five Years 40,000,000  
Capital Leases, Future Minimum Payments Due Thereafter 200,000,000  
Capital Leases, Future Minimum Payments Due 394,000,000  
Capital Leases, Future Minimum Payments, Interest Included in Payments 170,000,000  
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments 224,000,000  
Total Leases Future Minimum Payments [Abstract]    
Total Leases, Future Minimum Payments Due, Current 81,000,000  
Total Leases, Future Minimum Payments Due in Two Years 76,000,000  
Total Leases, Future Minimum Payments Due in Three Years 65,000,000  
Total Leases, Future Minimum Payments Due in Four Years 62,000,000  
Total Leases, Future Minimum Payments Due in Five Years 65,000,000  
Total Leases, Future Minimum Payments Due Thereafter 343,000,000  
Total Leases, Future Minimum Payments Due 692,000,000  
Total Leases, Future Minimum Payments, Interest Included in Payments 280,000,000  
Total Leases, Future Minimum Payments, Present Value of Net Minimum Payments 412,000,000  
Lease Assets, Historical Cost 1,000,000,000 1,000,000,000
Lease Assets, Accumulated Depreciation $ 340,000,000 $ 312,000,000
[1] Amounts are accounted for as financing transactions under U.S. GAAP and are included in our project financing, notes payable and other amounts above.