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
Balance (in shares) at Dec. 31, 2018		23,933	(10,116)
Balance at Dec. 31, 2018	$ 262,960	$ 239	$ (275,889)	$ 276,103	$ (20,281)	$ 282,788
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,005)					(1,005)
Currency translation adjustment	1,733				1,733
Shares issued for employee benefit plan and compensation (in shares)		78
Shares issued for employee benefit plan and compensation	347	$ 1		346
Purchase of treasury shares (in shares)			(43)
Purchase of treasury shares	(1,215)		$ (1,215)
Shares issued to directors (in shares)		8
Shares issued to directors	0	$ 0
Employee and director stock-based compensation	1,918			1,918
Performance-based common stock warrants	434			434
Balance (in shares) at Mar. 31, 2019		24,019	(10,159)
Balance at Mar. 31, 2019	265,172	$ 240	$ (277,104)	278,801	(18,548)	281,783
Balance (in shares) at Dec. 31, 2018		23,933	(10,116)
Balance at Dec. 31, 2018	262,960	$ 239	$ (275,889)	276,103	(20,281)	282,788
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,397)
Currency translation adjustment	$ (5,557)
Purchase of treasury shares (in shares)	(55)
Purchase of treasury shares	$ (1,741)
Balance (in shares) at Sep. 30, 2019		24,099	(10,171)
Balance at Sep. 30, 2019	261,651	$ 241	$ (277,630)	285,487	(25,838)	279,391
Balance (in shares) at Mar. 31, 2019		24,019	(10,159)
Balance at Mar. 31, 2019	265,172	$ 240	$ (277,104)	278,801	(18,548)	281,783
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(5,061)					(5,061)
Currency translation adjustment	(1,833)				(1,833)
Shares issued for employee benefit plan and compensation (in shares)		17
Shares issued for employee benefit plan and compensation	273			273
Purchase of treasury shares (in shares)			(5)
Purchase of treasury shares	(189)		$ (189)
Shares issued to directors (in shares)		7
Shares issued to directors	0	$ 0		0
Employee and director stock-based compensation	2,273			2,273
Performance-based common stock warrants	236			236
Balance (in shares) at Jun. 30, 2019		24,043	(10,164)
Balance at Jun. 30, 2019	260,871	$ 240	$ (277,293)	281,583	(20,381)	276,722
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,669					2,669
Currency translation adjustment	(5,457)				(5,457)
Shares issued for employee benefit plan and compensation (in shares)		29
Shares issued for employee benefit plan and compensation	256	$ 1		255
Purchase of treasury shares (in shares)			(7)
Purchase of treasury shares	(337)		$ (337)
Stock options exercised (in shares)		20
Stock options exercised	411			411
Shares issued to directors (in shares)		7
Shares issued to directors	0	$ 0		0
Employee and director stock-based compensation	2,527			2,527
Performance-based common stock warrants	711			711
Balance (in shares) at Sep. 30, 2019		24,099	(10,171)
Balance at Sep. 30, 2019	261,651	$ 241	$ (277,630)	285,487	(25,838)	279,391
Balance (in shares) at Dec. 31, 2019		24,118	(10,174)
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 (loss)	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)
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
Balance (in shares) at Mar. 31, 2020		24,256	(10,343)
Balance at Mar. 31, 2020	269,959	$ 243	$ (284,108)	291,350	(29,790)	292,264
Balance (in shares) at Dec. 31, 2019		24,118	(10,174)
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 (loss)	26,414
Currency translation adjustment	$ (2,774)
Purchase of treasury shares (in shares)	(263)
Purchase of treasury shares	$ (9,822)
Stock options exercised (in shares)	0
Balance (in shares) at Sep. 30, 2020		24,293	(10,437)
Balance at Sep. 30, 2020	$ 296,555	$ 243	$ (287,639)	296,674	(25,555)	312,832
Balance (in shares) at Mar. 31, 2020		24,256	(10,343)
Balance at Mar. 31, 2020	269,959	$ 243	$ (284,108)	291,350	(29,790)	292,264
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	14,400					14,400
Currency translation adjustment	(770)				(770)
Shares issued for employee benefit plan and compensation (in shares)		13
Shares issued for employee benefit plan and compensation	212	$ 0		212
Purchase of treasury shares (in shares)			(3)
Purchase of treasury shares	(114)		$ (114)
Employee and director stock-based compensation	2,291			2,291
Performance-based common stock warrants	154			154
Balance (in shares) at Jun. 30, 2020		24,269	(10,346)
Balance at Jun. 30, 2020	286,132	$ 243	$ (284,222)	294,007	(30,560)	306,664
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	6,168					6,168
Currency translation adjustment	5,005				5,005
Shares issued for employee benefit plan and compensation (in shares)		15
Shares issued for employee benefit plan and compensation	220	$ 0		220
Purchase of treasury shares (in shares)			(91)
Purchase of treasury shares	(3,417)		$ (3,417)
Shares issued to directors (in shares)		9
Shares issued to directors	0	$ 0		0
Employee and director stock-based compensation	2,260			2,260
Performance-based common stock warrants	187			187
Balance (in shares) at Sep. 30, 2020		24,293	(10,437)
Balance at Sep. 30, 2020	$ 296,555	$ 243	$ (287,639)	$ 296,674	$ (25,555)	$ 312,832