Liquidity Considerations Liquidiity Considerations - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Long-term Debt, Gross	$ 7,115	$ 25,600
Contractual Obligation, Future Minimum Payments Due, Remainder of Fiscal Year	274
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	62
Contractual Obligation, Due in Second Year	710
Long-term Debt, Maturities, Repayments of Principal in Year Two	141
Interest Expense [Member]
Other Commitments [Line Items]
Other Commitments, Future Minimum Payments, Remainder of Fiscal Year	212
Other Commitment, Due in Second Year	$ 569