Financial Instruments And Risk Management (Balance Sheet Classification And Fair Value Of Derivative Instruments) (Details) - Currency Forward Contracts [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
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	$ 16,603	$ 11,818	$ 7,262
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	1,857	1,797	865
Other Noncurrent Assets [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	4,830	9,922	7,963
Accrued Liabilities [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	201	47	584
Accrued Liabilities [Member] | Derivative Instruments Not Designated As Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	320	970	154
Other Long Term Liabilities [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	$ 109	$ 1	$ 0