Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 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			(202)
Other comprehensive income (loss)	$ (2,367)	$ 2,325	(202)	$ 3,289
Accumulated other comprehensive loss, net of tax, ending balance	(8,351)		(8,351)
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			(1,320)
Other comprehensive income (loss)			(1,320)
Accumulated other comprehensive loss, net of tax, ending balance	(10,887)		(10,887)
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			1,077
Other comprehensive income (loss)			1,077
Accumulated other comprehensive loss, net of tax, ending balance	2,555		2,555
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			41
Other comprehensive income (loss)			41
Accumulated other comprehensive loss, net of tax, ending balance	0		0
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 (loss)			0
Accumulated other comprehensive loss, net of tax, ending balance	$ (19)		$ (19)