Debt Obligations Debt Obligations Receivables Securitization Facility (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Trade Receivables Securitization Facility, Maximum Borrowing Base	$ 200
Trade Receivables Securitization Facility, Collateral At Period End	$ 426	$ 368
Federal Funds Rate [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%