Fair Value Fair Value (Schedule of Fair Value Measurements, Liabilities, Using Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	$ 201	$ 269
Transfers into Level 3, Liabilities	0	0
Transfers out of Level 3, Liabilities	0	0
Recorded in Revenue, Liabilities	(104)	(111)
Recorded in Other Comprehensive Income, Liabilities	0	0
Purchases, Liabilities	0	(7)
Issuances, Liabilities	133	253
Sales, Liabilities	0	(7)
Settlements, Liabilities	(115)	(196)
Fair Value, ending balance, Liabilities	115	201
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	(27)	(50)
Accrued Expenses And Other Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	20	0
Recorded in Revenue, Liabilities	0	0
Purchases, Liabilities		0
Issuances, Liabilities	0	20
Sales, Liabilities		0
Settlements, Liabilities	(20)	0
Fair Value, ending balance, Liabilities	0	20
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	0
Derivative Financial Instruments, Liabilities [Member] | Accrued Expenses And Other Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	181	269
Transfers into Level 3, Liabilities
Transfers out of Level 3, Liabilities
Recorded in Revenue, Liabilities	(104)	(111)
Recorded in Other Comprehensive Income, Liabilities
Purchases, Liabilities		(7)
Issuances, Liabilities	133	233
Sales, Liabilities		(7)
Settlements, Liabilities	(95)	(196)
Fair Value, ending balance, Liabilities	115	181
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	(27)	(50)
Foreign exchange contracts [Member] | Accrued Expenses And Other Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	161	260
Recorded in Revenue, Liabilities	(93)	(122)
Issuances, Liabilities	133	219
Settlements, Liabilities	(95)	(196)
Fair Value, ending balance, Liabilities	106	161
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	(27)	(60)
Interest rate contracts [Member] | Accrued Expenses And Other Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	11	0
Recorded in Revenue, Liabilities	(11)	11
Purchases, Liabilities		(7)
Issuances, Liabilities	0	14
Sales, Liabilities		(7)
Settlements, Liabilities	0	0
Fair Value, ending balance, Liabilities	0	11
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	0	10
Other [Member] | Accrued Expenses And Other Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	9	9
Recorded in Revenue, Liabilities	0	0
Purchases, Liabilities		0
Issuances, Liabilities		0
Sales, Liabilities		0
Settlements, Liabilities	0	0
Fair Value, ending balance, Liabilities	9	9
Change in Unrealized Gains (Losses) Related to Financial Instruments, Liabilities, Held at Period End	$ 0	$ 0