Derivatives and Hedging Notional and fair values of derivative instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Derivatives, Fair Value
Notional Amount	$ 1,290		$ 1,577
Derivative Assets	55	[1]	80	[1]
Derivative Liabilities	65	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	40	[3]	50	[3]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	50	[4]	63	[4]
Other Current Assets [Member]
Derivatives, Fair Value
Derivative Assets	25		46
Net Amounts of Assets Presented in the Statement of Financial Position	13		18
Other Noncurrent Assets [Member]
Derivatives, Fair Value
Derivative Assets	30		34
Net Amounts of Assets Presented in the Statement of Financial Position	27		32
Other Current Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	17		51
Net Amounts of Liabilities Presented in the Statement of Financial Position	5		23
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	48		42
Net Amounts of Liabilities Presented in the Statement of Financial Position	45		40
Derivatives accounted for as hedges [Member]
Derivatives, Fair Value
Notional Amount	1,106		1,362
Derivative Assets	55	[1]	80	[1]
Derivative Liabilities	65	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	40	[3]	50	[3]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	50	[4]	63	[4]
Derivatives accounted for as hedges [Member] | Interest rate contracts [Member]
Derivatives, Fair Value
Notional Amount	0		171
Derivative Assets	0	[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	0	[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	1,106		1,191
Derivative Assets	55	[1]	71	[1]
Derivative Liabilities	65	[2]	93	[2]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Assets Presented in the Statement of Financial Position	40	[3]	41	[3]
Gross Amounts Offset in the Statement of Financial Position	(15)		(30)
Net Amounts of Liabilities Presented in the Statement of Financial Position	50	[4]	63	[4]
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	184		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 ($25 million and $46 million at September 30, 2014 and December 31, 2013, respectively) or Other non-current assets ($30 million and $34 million at September 30, 2014 and December 31, 2013, respectively).

[2] Included within Other current liabilities ($17 million and $51 million at September 30, 2014 and December 31, 2013, respectively) or Other non-current liabilities ($48 million and $42 million at September 30, 2014 and December 31, 2013, respectively).

[3] Included within Other current assets ($13 million and $18 million at September 30, 2014 and December 31, 2013, respectively) or Other non-current assets ($27 million and $32 million at September 30, 2014 and December 31, 2013, respectively).

[4] Included within Other current liabilities ($5 million and $23 million at September 30, 2014 and December 31, 2013, respectively) or Other non-current liabilities ($45 million and $40 million at September 30, 2014 and December 31, 2013, respectively).