Annual report pursuant to Section 13 and 15(d)

Financial Instruments and Risk Management (Balance Sheet Classification and Fair Value of Derivative Instruments) (Details)

v3.6.0.2
Financial Instruments and Risk Management (Balance Sheet Classification and Fair Value of Derivative Instruments) (Details) - Forward Contracts [Member] - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Not Designated as Hedging Instrument [Member] | Prepaid Expenses And Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Fair value of derivative assets $ 1,361 $ 1,328
Not Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Fair value of derivative liabilities 180 1,693
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Prepaid Expenses And Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Fair value of derivative assets 9,805 5,394
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member]    
Derivatives, Fair Value [Line Items]    
Fair value of derivative assets 1,969 566
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Fair value of derivative liabilities $ 106 $ 224