Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss By Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	$ (13,016)	$ (9,475)	$ (9,094)
Other comprehensive gain (loss) before reclassifications	(1,159)	(3,528)	(3,281)
Amounts reclassified from accumulated other comprehensive loss	(1)	(13)	2,900
Other comprehensive loss	(1,160)	(3,541)	(381)
Accumulated other comprehensive loss, net of tax, ending balance	(14,176)	(13,016)	(9,475)
Foreign currency translaction adjustments [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	(13,079)	(9,688)	(8,090)
Other comprehensive gain (loss) before reclassifications	(1,465)	(3,391)	(4,528)
Amounts reclassified from accumulated other comprehensive loss	0	0	2,930
Other comprehensive loss	(1,465)	(3,391)	(1,598)
Accumulated other comprehensive loss, net of tax, ending balance	(14,544)	(13,079)	(9,688)
Derivative instruments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	0	0	0
Other comprehensive gain (loss) before reclassifications	286	0	0
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive loss	286	0	0
Accumulated other comprehensive loss, net of tax, ending balance	286	0	0
Unrealized loss on investments, net of tax [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	(95)	(64)	(1,433)
Other comprehensive gain (loss) before reclassifications	21	(31)	1,369
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive loss	21	(31)	1,369
Accumulated other comprehensive loss, net of tax, ending balance	(74)	(95)	(64)
Other [Member]
Accumulated other comprehensive income loss [Line Items]
Accumulated other comprehensive loss, net of tax, beginning balance	158	277	429
Other comprehensive gain (loss) before reclassifications	(1)	(106)	(122)
Amounts reclassified from accumulated other comprehensive loss	(1)	(13)	(30)
Other comprehensive loss	(2)	(119)	(152)
Accumulated other comprehensive loss, net of tax, ending balance	$ 156	$ 158	$ 277