Financial Instruments - Financial Position, Fair Value (Details) - Foreign currency exchange contract [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Fair Value Derivative Assets	$ 1,307	$ 10,625
Fair Value Derivative Liabilities	11,826	3,780
Designated as hedging instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair Value Derivative Assets	0	813
Fair Value Derivative Liabilities	0	0
Designated as hedging instrument [Member] | Accrued liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair Value Derivative Assets	0	0
Fair Value Derivative Liabilities	11,826	1,428
Not designated as hedging instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair Value Derivative Assets	1,307	9,812
Fair Value Derivative Liabilities	0	0
Not designated as hedging instrument [Member] | Accrued liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair Value Derivative Assets	0	0
Fair Value Derivative Liabilities	$ 0	$ 2,352