Derivatives and Hedging (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Derivatives, Fair Value
Notional Amount	$ 1,692		$ 1,849
Derivative Assets	56		210
Derivative Liabilities	111		251
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Assets Presented in the Statement of Financial Position	36	[1]	50	[1]
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Liabilities Presented in the Statement of Financial Position	91	[2]	91	[2]
Derivatives accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	1,397		1,544
Derivative Assets	55		208
Derivative Liabilities	110		250
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Assets Presented in the Statement of Financial Position	35	[1]	48	[1]
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Liabilities Presented in the Statement of Financial Position	90	[2]	90	[2]
Interest rate contracts [Member] | Derivatives accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	325		336
Derivative Assets	16		17
Derivative Liabilities	0		0
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Assets Presented in the Statement of Financial Position	16	[1]	17	[1]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Liabilities Presented in the Statement of Financial Position	0	[2]	0	[2]
Foreign exchange contracts [Member] | Derivatives accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	1,072		1,208
Derivative Assets	39		191
Derivative Liabilities	110		250
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Assets Presented in the Statement of Financial Position	19	[1]	31	[1]
Gross Amounts Offset in the Statement of Financial Position	(20)		(160)
Net Amounts of Liabilities Presented in the Statement of Financial Position	90	[2]	90	[2]
Foreign exchange contracts [Member] | Derivatives not accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	295		305
Derivative Assets	1		2
Derivative Liabilities	1		1
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Assets Presented in the Statement of Financial Position	1	[1]	2	[1]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Liabilities Presented in the Statement of Financial Position	$ 1	[2]	$ 1	[2]

[1] Included within Other current assets or Other non-current assets

[2] Included within Other current liabilities or Other non-current liabilities