Fair Value - Schedule of Fair Value Measurements, Liabilities, Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	$ 50	$ 19	$ 83	$ 26
Recorded in Revenue, Liabilities	(3)	36	24	22
Issuances, Liabilities	(1)	(18)	(19)	(28)
Settlements, Liabilities	(26)	(5)	(104)	(8)
Fair Value, ending balance, Liabilities	22	68	22	68
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	1	35	(2)	32
Derivative instruments, liabilities | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	50	19	83	26
Recorded in Revenue, Liabilities	(3)	36	24	22
Issuances, Liabilities	(1)	(18)	(19)	(28)
Settlements, Liabilities	(26)	(5)	(104)	(8)
Fair Value, ending balance, Liabilities	22	68	22	68
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	1	35	(2)	32
Foreign exchange contracts | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	50	10	74	17
Recorded in Revenue, Liabilities	(3)	36	24	22
Issuances, Liabilities	(1)	(18)	(19)	(28)
Settlements, Liabilities	(26)	(5)	(95)	(8)
Fair Value, ending balance, Liabilities	22	59	22	59
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	1	35	(2)	32
Other | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities		9	9	9
Recorded in Revenue, Liabilities		0	0	0
Issuances, Liabilities		0	0	0
Settlements, Liabilities		0	(9)	0
Fair Value, ending balance, Liabilities	$ 0	9	0	9
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period		$ 0	$ 0	$ 0