Condensed Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Total
Balance at Dec. 31, 2019	$ 390		$ 271,782		$ 36,704	$ (8,589)	$ (14,591)		$ 285,696
Balance, shares at Dec. 31, 2019	39,018						(1,484)
Net loss					(6,665)				(6,665)
Other comprehensive loss:
Other comprehensive loss						(4,463)			(4,463)
Equity compensation	$ 2		2,687						2,689
Equity compensation, shares	208
Exercise of options			376						376
Exercise of options, shares	33
Employee stock purchase plan			688						688
Employee stock purchase plan, shares	30
Redemption and repurchase of stock to cover tax withholdings			(1,712)						(1,712)
Redemption and repurchase of stock to cover tax withholdings, shares	(70)
Balance at Mar. 31, 2020	$ 392		273,821		30,039	(13,052)	$ (14,591)		276,609
Balance, shares at Mar. 31, 2020	39,219						(1,484)
Balance (Accounting Standards Update 2020-06 [Member]) at Dec. 31, 2020		$ 16,400		$ 3,200
Balance at Dec. 31, 2020	$ 404		316,192		20,022	6,743	$ (14,648)		328,713
Balance, shares at Dec. 31, 2020	40,394						(1,487)
Net loss					(3,138)				(3,138)
Other comprehensive loss:
Other comprehensive loss						(10,290)			(10,290)
Equity compensation	$ 2		2,635						2,637
Equity compensation, shares	207
Exercise of options			271						271
Exercise of options, shares	19
Employee stock purchase plan	$ 1		589						590
Employee stock purchase plan, shares	37
Redemption and repurchase of stock to cover tax withholdings	$ (1)		(1,812)						(1,813)
Redemption and repurchase of stock to cover tax withholdings, shares	(72)
Balance (Accounting Standards Update 2020-06 [Member]) at Mar. 31, 2021		$ (16,426)		$ (3,213)				$ (19,639)
Balance at Mar. 31, 2021	$ 406		$ 301,449		$ 13,671	$ (3,547)	$ (14,648)		$ 297,331
Balance, shares at Mar. 31, 2021	40,585						(1,487)