Derivative Instruments Fair Value of Derivative Contracts (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative liability offset against collateral	$ 21
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Reported in Other Current Liabilities	119	151
Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Reported in Other Current Assets	21	44
Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Derivative asset offset against collateral	21
Foreign Exchange Contract | Other Current Assets
Derivatives, Fair Value [Line Items]
Net derivative liability	98
Foreign Exchange Contract | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Reported in Other Current Liabilities	22	30
Foreign Exchange Contract | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Reported in Other Current Assets	15	29
Cash Flow Hedging | Foreign Exchange Contract | Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Reported in Other Current Liabilities	97	121
Cash Flow Hedging | Foreign Exchange Contract | Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Reported in Other Current Assets	$ 6	$ 15