Financial Instruments And Risk Management (Gross Notional Amount Of Outstanding Derivative Instruments) (Details) - Currency Forward Contracts [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Derivative Instruments Designated As Cash Flow Hedges [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency forward contracts	$ 233,500	$ 206,000	$ 228,500
Derivative Instruments Not Designated As Cash Flow Hedges [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency forward contracts	$ 168,361	$ 184,940	$ 60,785