CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Issued	Common Stock in Treasury	Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2019		24,118	(10,174)
Beginning balance at Dec. 31, 2019	$ 274,399	$ 241	$ (277,817)	$ 288,338	$ (22,781)	$ 286,418
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,846					5,846
Currency translation adjustment	(7,009)				(7,009)
Shares issued for employee benefit plan and compensation (in shares)		129
Shares issued for employee benefit plan and compensation	$ 527	$ 1		526
Purchase of treasury shares (in shares)	(169)		(169)
Purchase of treasury shares	$ (6,291)		$ (6,291)
Shares issued to directors (in shares)		9
Shares issued to directors	0	$ 1		(1)
Employee and director stock-based compensation	2,303			2,303
Performance-based common stock warrants	184			184
Ending balance (in shares) at Mar. 31, 2020		24,256	(10,343)
Ending balance at Mar. 31, 2020	269,959	$ 243	$ (284,108)	291,350	(29,790)	292,264
Beginning balance (in shares) at Dec. 31, 2020		24,392	(10,618)
Beginning balance at Dec. 31, 2020	313,301	$ 244	$ (295,495)	302,084	(18,522)	324,990
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,993					6,993
Currency translation adjustment	(2,868)				(2,868)
Shares issued for employee benefit plan and compensation (in shares)		160
Shares issued for employee benefit plan and compensation	$ 410	$ 2		408
Purchase of treasury shares (in shares)	(191)		(191)
Purchase of treasury shares	$ (10,951)		$ (10,951)
Stock options exercised (in shares)	22	22
Stock options exercised	$ 991			991
Shares issued to directors (in shares)		7
Shares issued to directors	0
Employee and director stock-based compensation	2,600			2,600
Performance-based common stock warrants	143			143
Ending balance (in shares) at Mar. 31, 2021		24,581	(10,809)
Ending balance at Mar. 31, 2021	$ 310,619	$ 246	$ (306,446)	$ 306,226	$ (21,390)	$ 331,983