Debt Obligations Level 4 (Details) - Scheduled Maturities (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Debt and Commitments Maturities [Line Items]      
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months $ 98    
Operating Leases, Future Minimum Payments Due, Next Twelve Months 35    
Capital Leases, Future Minimum Payments Due, Next Twelve Months 2    
Long-term Debt, Maturities, Repayments of Principal in Year Two 34    
Capital Leases, Future Minimum Payments Due in Two Years 2    
Operating Leases, Future Minimum Payments, Due in Two Years 30    
Long-term Debt, Maturities, Repayments of Principal in Year Three 42    
Capital Leases, Future Minimum Payments Due in Three Years 2    
Operating Leases, Future Minimum Payments, Due in Three Years 22    
Long-term Debt, Maturities, Repayments of Principal in Year Four 1,261    
Capital Leases, Future Minimum Payments Due in Four Years 2    
Operating Leases, Future Minimum Payments, Due in Four Years 16    
Long-term Debt, Maturities, Repayments of Principal in Year Five 0    
Capital Leases, Future Minimum Payments Due in Five Years 2    
Operating Leases, Future Minimum Payments, Due in Five Years 8    
Long-term Debt, Maturities, Repayments of Principal after Year Five 2,387    
Capital Leases, Future Minimum Payments Due Thereafter 5    
Operating Leases, Future Minimum Payments, Due Thereafter 17    
Capital Leases, Future Minimum Payments Due 15    
Operating Leases, Future Minimum Payments Due 128    
Amount representing interest (6)    
Present value of minimum payments 9    
Rental Expense under Operating Leases 36 36 36
Non-affiliated Debt [Member]      
Debt and Commitments Maturities [Line Items]      
Total minimum payments $ 3,822