Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2017	$ 376	$ 249,935	$ 37,609	$ 1,857	$ (12,719)	$ 277,058
Balance, shares at Dec. 31, 2017	37,618				(1,386)
Net (loss) income | ASU 606 [Member]			(2,064)			(2,064)
Net (loss) income						(2,064)
Foreign currency translation adjustment | ASU 606 [Member]				(5,140)		(5,140)
Foreign currency translation adjustment						(5,140)
Comprehensive loss | ASU 606 [Member]						(6,989)
Comprehensive loss						(7,204)
Equity compensation	$ 2	5,046				5,048
Equity compensation, shares	275
Exercise of options	$ 6	4,320			$ (1,872)	2,454
Exercise of options, shares	572				(98)
Employee stock purchase plan	$ 1	1,338				1,339
Employee stock purchase plan, shares	83
Redemption and repurchase of stock to cover tax withholdings	$ (1)	(2,084)				(2,085)
Redemption and repurchase of stock to cover tax withholdings, shares	(103)
Balance at Sep. 30, 2018	$ 384	258,555	35,760	(3,283)	$ (14,591)	276,825
Balance, shares at Sep. 30, 2018	38,445				(1,484)
Balance at Jun. 30, 2018	$ 382	254,288	34,195	(2,769)	$ (14,591)	271,505
Balance, shares at Jun. 30, 2018	38,204				(1,484)
Net (loss) income			1,565			1,565
Foreign currency translation adjustment				(514)		(514)
Comprehensive loss						1,051
Equity compensation	$ 1	1,692				1,693
Equity compensation, shares	(14)
Exercise of options	$ 1	2,098				2,099
Exercise of options, shares	218
Employee stock purchase plan	$ 1	750				751
Employee stock purchase plan, shares	46
Redemption and repurchase of stock to cover tax withholdings	$ (1)	(273)				(274)
Redemption and repurchase of stock to cover tax withholdings, shares	(9)
Balance at Sep. 30, 2018	$ 384	258,555	35,760	(3,283)	$ (14,591)	276,825
Balance, shares at Sep. 30, 2018	38,445				(1,484)
Balance at Jun. 30, 2018	$ 382	254,288	34,195	(2,769)	$ (14,591)	271,505
Balance, shares at Jun. 30, 2018	38,204				(1,484)
Balance at Sep. 30, 2019	$ 390	269,192	37,385	(14,875)	$ (14,591)	277,501
Balance, shares at Sep. 30, 2019	38,988				(1,484)
Cumulative effect of adjustment | ASU 606 [Member]			215			215
Balance at Dec. 31, 2018	$ 385	260,361	34,984	(6,072)	$ (14,591)	275,067
Balance, shares at Dec. 31, 2018	38,463				(1,484)
Net (loss) income			2,401			2,401
Foreign currency translation adjustment				(8,803)		(8,803)
Comprehensive loss						(6,402)
Equity compensation	$ 2	7,037				7,039
Equity compensation, shares	251
Exercise of options	$ 3	3,054				3,057
Exercise of options, shares	306
Employee stock purchase plan	$ 1	1,462				1,463
Employee stock purchase plan, shares	61
Redemption and repurchase of stock to cover tax withholdings	$ (1)	(2,722)				(2,723)
Redemption and repurchase of stock to cover tax withholdings, shares	(93)
Balance at Sep. 30, 2019	$ 390	269,192	37,385	(14,875)	$ (14,591)	277,501
Balance, shares at Sep. 30, 2019	38,988				(1,484)
Balance at Jun. 30, 2019	$ 389	265,694	37,519	(6,858)	$ (14,591)	282,153
Balance, shares at Jun. 30, 2019	38,943				(1,484)
Net (loss) income			(134)			(134)
Foreign currency translation adjustment				(8,017)		(8,017)
Comprehensive loss						(8,151)
Equity compensation		2,620				2,620
Equity compensation, shares	6
Exercise of options		53				53
Exercise of options, shares	5
Employee stock purchase plan	$ 1	884				885
Employee stock purchase plan, shares	36
Redemption and repurchase of stock to cover tax withholdings		(59)				(59)
Redemption and repurchase of stock to cover tax withholdings, shares	(2)
Balance at Sep. 30, 2019	$ 390	$ 269,192	$ 37,385	$ (14,875)	$ (14,591)	$ 277,501
Balance, shares at Sep. 30, 2019	38,988				(1,484)