Fair Value (Schedule of Fair Value Measurements, Liabilities, Using Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	$ 117	$ 166	$ 115	$ 201
Transfers into Level 3, Liabilities	0	0	0	0
Transfers out of Level 3, Liabilities	0	0	0	0
Recorded in Revenue, Liabilities	(17)	(58)	59	(142)
Recorded in Other Comprehensive Income, Liabilities	0	0	0	0
Purchases, Liabilities	0	0	0	0
Issuances, Liabilities	5	76	24	162
Sales, Liabilities	0	0	0	0
Settlements, Liabilities	(41)	(75)	(134)	(112)
Fair Value, ending balance, Liabilities	64	109	64	109
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of September 30, 2012	(15)	(43)	15	(70)
Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities				20
Recorded in Revenue, Liabilities				0
Purchases, Liabilities
Issuances, Liabilities				0
Sales, Liabilities
Settlements, Liabilities				(20)
Fair Value, ending balance, Liabilities		0		0
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	117	166	115	181
Recorded in Revenue, Liabilities	(17)	(58)	59	(142)
Issuances, Liabilities	5	76	24	162
Settlements, Liabilities	(41)	(75)	(134)	(92)
Fair Value, ending balance, Liabilities	64	109	64	109
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of September 30, 2012	(15)	(43)	15	(70)
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	108	157	106	161
Recorded in Revenue, Liabilities	(17)	(58)	59	(131)
Issuances, Liabilities	5	76	24	162
Sales, Liabilities
Settlements, Liabilities	(41)	(75)	(134)	(92)
Fair Value, ending balance, Liabilities	55	100	55	100
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of September 30, 2012	(15)	(43)	15	(70)
Interest-rate contracts | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities				11
Recorded in Revenue, Liabilities				(11)
Purchases, Liabilities
Issuances, Liabilities				0
Sales, Liabilities
Settlements, Liabilities				0
Fair Value, ending balance, Liabilities		0		0
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of September 30, 2012				0
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	9
Recorded in Revenue, Liabilities	0	0	0	0
Purchases, Liabilities
Issuances, Liabilities	0	0	0	0
Sales, Liabilities
Settlements, Liabilities	0	0	0	0
Fair Value, ending balance, Liabilities	9	9	9	9
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of September 30, 2012	$ 0	$ 0	$ 0	$ 0