Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance			$ (14,176)
Other comprehensive gain (loss) before reclassifications			4,694
Net current period other comprehensive gain (loss)	$ 1,405	$ 1,064	4,694	$ (1,303)
Accumulated other comprehensive loss, net of tax, ending balance	(9,482)		(9,482)
Foreign currency translaction adjustments [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance			(14,544)
Other comprehensive gain (loss) before reclassifications			4,434
Net current period other comprehensive gain (loss)			4,434
Accumulated other comprehensive loss, net of tax, ending balance	(10,110)		(10,110)
Derivative instruments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance			286
Other comprehensive gain (loss) before reclassifications			254
Net current period other comprehensive gain (loss)			254
Accumulated other comprehensive loss, net of tax, ending balance	540		540
Unrealized loss on investments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance			(74)
Other comprehensive gain (loss) before reclassifications			19
Net current period other comprehensive gain (loss)			19
Accumulated other comprehensive loss, net of tax, ending balance	(55)		(55)
Other [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance			156
Other comprehensive gain (loss) before reclassifications			(13)
Net current period other comprehensive gain (loss)			(13)
Accumulated other comprehensive loss, net of tax, ending balance	$ 143		$ 143