Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss By Component) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	$ (8,149)
Other comprehensive gain (loss) before reclassifications	2,165
Other comprehensive income	2,165	$ 964
Accumulated other comprehensive loss, net of tax, ending balance	(5,984)
Foreign currency translaction adjustments [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	(9,567)
Other comprehensive gain (loss) before reclassifications	1,332
Other comprehensive income	1,332
Accumulated other comprehensive loss, net of tax, ending balance	(8,235)
Derivative instruments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	1,478
Other comprehensive gain (loss) before reclassifications	833
Other comprehensive income	833
Accumulated other comprehensive loss, net of tax, ending balance	2,311
Unrealized loss on investments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	(41)
Other comprehensive gain (loss) before reclassifications	0
Other comprehensive income	0
Accumulated other comprehensive loss, net of tax, ending balance	(41)
Other, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	(19)
Other comprehensive gain (loss) before reclassifications	0
Other comprehensive income	0
Accumulated other comprehensive loss, net of tax, ending balance	$ (19)