Derivatives and Hedging Notional and fair values of derivative instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Derivatives, Fair Value
Notional Amount	$ 1,572		$ 1,577
Derivative Assets	82	[1]	80	[1]
Derivative Liabilities	94	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	58	[3]	50	[3]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	70	[4]	63	[4]
Other Current Assets [Member]
Derivatives, Fair Value
Derivative Assets	49		46
Net Amounts of Assets Presented in the Statement of Financial Position	21		18
Other Noncurrent Assets [Member]
Derivatives, Fair Value
Derivative Assets	33		34
Net Amounts of Assets Presented in the Statement of Financial Position	37		32
Other Current Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	18		51
Net Amounts of Liabilities Presented in the Statement of Financial Position	18		23
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	76		42
Net Amounts of Liabilities Presented in the Statement of Financial Position	52		40
Derivatives accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	1,395		1,362
Derivative Assets	82	[1]	80	[1]
Derivative Liabilities	94	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	58	[3]	50	[3]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	70	[4]	63	[4]
Derivatives accounted for as hedges [Member] | Interest rate contracts [Member]
Derivatives, Fair Value
Notional Amount	172		171
Derivative Assets	9	[1]	9	[1]
Derivative Liabilities	0	[2]	0	[2]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Assets Presented in the Statement of Financial Position	9	[3]	9	[3]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Liabilities Presented in the Statement of Financial Position	0	[4]	0	[4]
Derivatives accounted for as hedges [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	1,223		1,191
Derivative Assets	73	[1]	71	[1]
Derivative Liabilities	94	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	49	[3]	41	[3]
Gross Amounts Offset in the Statement of Financial Position	(24)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	70	[4]	63	[4]
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	177		215
Derivative Assets	0	[1]	0	[1]
Derivative Liabilities	0	[2]	0	[2]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Assets Presented in the Statement of Financial Position	0	[3]	0	[3]
Gross Amounts Offset in the Statement of Financial Position	0		0
Net Amounts of Liabilities Presented in the Statement of Financial Position	$ 0	[4]	$ 0	[4]

[1] Included within Other current assets ($49 million and $46 million at March 31, 2014 and December 31, 2013, respectively) or Other non-current assets ($33 million and $34 million at March 31, 2014 and December 31, 2013, respectively)

[2] Included within Other current liabilities ($18 million and $51 million at March 31, 2014 and December 31, 2013, respectively) or Other non-current liabilities ($76 million and $42 million at March 31, 2014 and December 31, 2013, respectively)

[3] Included within Other current assets ($21 million and $18 million at March 31, 2014 and December 31, 2013, respectively) or Other non-current assets ($37 million and $32 million at March 31, 2014 and December 31, 2013, respectively)

[4] Included within Other current liabilities ($18 million and $23 million at March 31, 2014 and December 31, 2013, respectively) or Other non-current liabilities ($52 million and $40 million at March 31, 2014 and December 31, 2013, respectively)