Derivative Instruments (Forward Currency Exchange Contracts) (Details) - Foreign Exchange Contract - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Amount	$ 3,874	$ 2,442
Maximum Term (Days)	546 days	546 days
Derivative, Fair Value, Net	$ 15	$ 20
Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	567	357
Derivative, Fair Value, Net	17	20
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	3,307	2,085
Derivative, Fair Value, Net	(2)	0
Other Current Assets
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	24	30
Other Current Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	18	18
Other Current Assets | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	6	12
Other Noncurrent Assets
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Other Noncurrent Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Other Noncurrent Assets | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Other Current Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability	(10)	(12)
Other Current Liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability	(2)	0
Other Current Liabilities | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (8)	$ (12)