Fair Value - Schedule of Fair Value Measurements, Liabilities, Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 5	$ 83
Total realized and unrealized (gains) losses recorded in revenue	5	109
Issuances		37
Settlements	(10)	(48)
Fair value, end of period	0	181
Change in unrealized (gains) losses related to financial instruments held	0	93
Derivative instruments, liabilities | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	5	83
Total realized and unrealized (gains) losses recorded in revenue	5	109
Issuances		37
Settlements	(10)	(48)
Fair value, end of period	0	181
Change in unrealized (gains) losses related to financial instruments held	0	93
Foreign exchange contracts | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	5	74
Total realized and unrealized (gains) losses recorded in revenue	5	109
Issuances		37
Settlements	(10)	(48)
Fair value, end of period	0	172
Change in unrealized (gains) losses related to financial instruments held	$ 0	93
Other | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		9
Total realized and unrealized (gains) losses recorded in revenue		0
Issuances		0
Settlements		0
Fair value, end of period		9
Change in unrealized (gains) losses related to financial instruments held		$ 0