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	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2014		22,910	(7,008)
Beginning balance at Dec. 31, 2014	$ 315,621	$ 229	$ (120,938)	$ 214,710	$ (4,446)	$ 226,066	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	29,173					29,174	(1)
Currency translation adjustment	(11,353)				(11,353)
Shares issued for employee benefit plan and compensation (in shares)		165
Shares issued for employee benefit plan and compensation	$ 868	$ 2		866
Purchase of treasury shares (in shares)	(1,817)		(1,817)
Purchase of treasury shares	$ (89,395)		$ (89,395)
Stock options exercised (in shares)	71	71
Stock options exercised	$ 1,712	$ 1		1,711
Shares Issued to Directors (in shares)		30
Shares issued to directors	0
Employee and director stock-based compensation	7,913			7,913
Tax benefit from exercise of non-qualified stock options and vested restricted stock	3,069			3,069
Business combination	378						378
Distribution to noncontrolling interest	(78)						(78)
Ending balance (in shares) at Dec. 31, 2015		23,176	(8,825)
Ending balance at Dec. 31, 2015	257,908	$ 232	$ (210,333)	228,269	(15,799)	255,240	299
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	20,384					20,354	30
Currency translation adjustment	(7,022)				(7,022)
Shares issued for employee benefit plan and compensation (in shares)		130
Shares issued for employee benefit plan and compensation	$ 913	$ 1		912
Purchase of treasury shares (in shares)	(198)		(198)
Purchase of treasury shares	$ (12,647)		$ (12,647)
Stock options exercised (in shares)	239	239
Stock options exercised	$ 6,244	$ 3		6,241
Shares Issued to Directors (in shares)		30
Shares issued to directors	0
Employee and director stock-based compensation	10,324			10,324
Tax benefit from exercise of non-qualified stock options and vested restricted stock	2,007			2,007
Performance-based common stock warrants	2,728			2,728
Deconsolidation of Encore Controls LLC	(329)						(329)
Ending balance (in shares) at Dec. 31, 2016		23,575	(9,023)
Ending balance at Dec. 31, 2016	280,510	$ 236	$ (222,980)	250,481	(22,821)	275,594	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact to retained earnings from adoption of ASU 2016-09	1,509					1,509
Beginning balance, adjusted	282,019	$ 236	$ (222,980)	250,481	(22,821)	277,103	0
Net income (loss)	(10,323)					(10,323)
Currency translation adjustment	6,222				6,222
Shares issued for employee benefit plan and compensation (in shares)		99
Shares issued for employee benefit plan and compensation	$ 648	$ 1		647
Purchase of treasury shares (in shares)	(680)		(680)
Purchase of treasury shares	$ (39,085)		$ (39,085)
Stock options exercised (in shares)	56	56
Stock options exercised	$ 1,442	$ 1		1,441
Shares Issued to Directors (in shares)		30
Shares issued to directors	0
Employee and director stock-based compensation	11,943			11,943
Performance-based common stock warrants	683			683
Ending balance (in shares) at Dec. 31, 2017		23,760	(9,703)
Ending balance at Dec. 31, 2017	$ 253,549	$ 238	$ (262,065)	$ 265,195	$ (16,599)	$ 266,780	$ 0