Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments And Risk Management (Balance Sheet Classification And Fair Value Of Derivative Instruments) (Details)

v3.10.0.1
Financial Instruments And Risk Management (Balance Sheet Classification And Fair Value Of Derivative Instruments) (Details) - Currency Forward Contracts [Member] - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Sep. 30, 2017
Prepaid Expenses And Other Current Assets [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative assets $ 7,262 $ 1,648 $ 1,930
Prepaid Expenses And Other Current Assets [Member] | Derivative Instruments Not Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative assets 865 683 959
Other Non-Current Assets [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative assets 7,963 335 509
Accrued Liabilities [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative liabilities 584 9,336 10,152
Accrued Liabilities [Member] | Derivative Instruments Not Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative liabilities 154 1,229 407
Other Long Term Liabilities [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]      
Derivatives, Fair Value [Line Items]      
Fair value of derivative liabilities $ 0 $ 3,820 $ 3,048