Derivative Financial Instruments (Summary Of Derivative Financial Instruments Notional Amounts On Outstanding Positions) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Total notional value	$ 224,680	$ 328,221
Derivative fair value	(406)	(157)
Singapore Dollar [Member]
Derivatives, Fair Value [Line Items]
Total notional value	73,455	94,763
Derivative fair value	364	(2,611)
Euro [Member]
Derivatives, Fair Value [Line Items]
Total notional value	37,718	71,228
Derivative fair value	(122)	(1,441)
Japanese Yen [Member]
Derivatives, Fair Value [Line Items]
Total notional value	30,688	87,171
Derivative fair value	(89)	4,180
South Korean Won [Member]
Derivatives, Fair Value [Line Items]
Total notional value	15,888	8,278
Derivative fair value	(134)	407
British Pound Sterling [Member]
Derivatives, Fair Value [Line Items]
Total notional value	13,233	14,332
Derivative fair value	80	(660)
Other Currencies [Member]
Derivatives, Fair Value [Line Items]
Total notional value	53,698	52,449
Derivative fair value	$ (505)	$ (32)