Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Beginning balances at Dec. 31, 2017	$ 246,396	$ 376	$ 74	$ 411,298	$ 256	$ (166,245)	$ (96)	$ 733
Beginning balances, shares at Dec. 31, 2017		37,544	74,436,579				29,990
Vesting of restricted stock units	1		$ 1
Vesting of restricted stock units, shares			519,362
Stock-based compensation	5,650			5,650
Proceeds from offering of common stock	27,967		$ 3	27,964
Proceeds from offering of common stock, shares			3,450,000
Issuance of common stock under employee stock purchase plan	668			668
Issuance of common stock under employee stock purchase plan, shares			81,525
Common stock issued as payment for MPUs	827			827
Common stock issued as payment for MPUs, shares			81,277
Exercise of SARs	1		$ 1
Exercise of SARs, shares			230,630
Net income (loss)	(20,387)					(20,603)		216
Series A convertible preferred stock dividend		$ 11				(11)
Series A convertible preferred stock dividend, shares		1,128
Foreign currency translation adjustments	(561)				(554)			(7)
Ending balances at Sep. 30, 2018	260,562	$ 387	$ 79	446,407	(298)	(186,859)	$ (96)	942
Ending balances, shares at Sep. 30, 2018		38,672	78,799,373				29,990
Beginning balances at Jun. 30, 2018	261,605	$ 387	$ 79	444,069	(141)	(183,564)	$ (96)	871
Beginning balances, shares at Jun. 30, 2018		38,672	78,593,002				29,990
Vesting of restricted stock units, shares			29,013
Stock-based compensation	2,338			2,338
Exercise of SARs, shares			177,358
Net income (loss)	(3,222)					(3,295)		73
Foreign currency translation adjustments	(159)				(157)			(2)
Ending balances at Sep. 30, 2018	260,562	$ 387	$ 79	446,407	(298)	(186,859)	$ (96)	942
Ending balances, shares at Sep. 30, 2018		38,672	78,799,373				29,990
Beginning balances at Dec. 31, 2018	257,858	$ 394	$ 79	449,343	(381)	(192,507)	$ (96)	1,026
Beginning balances, shares at Dec. 31, 2018		39,442	79,008,243				29,990
Vesting of restricted stock units	1		$ 1
Vesting of restricted stock units, shares			614,132
Stock-based compensation	5,920			5,920
Issuance of common stock under employee stock purchase plan	604			604
Issuance of common stock under employee stock purchase plan, shares			113,703
Common stock issued as payment for MPUs	502			502
Common stock issued as payment for MPUs, shares			60,885
Common stock repurchased under share repurchase program	(7,875)		$ (2)	(7,536)			$ (337)
Common stock repurchased under share repurchase program, Shares			(1,513,743)				68,286
Exercise of SARs, shares			3,032
Net income (loss)	(15,651)					(15,922)		271
Series A convertible preferred stock dividend		$ 12				(12)
Series A convertible preferred stock dividend, shares		1,182
Foreign currency translation adjustments	(779)				(751)			(28)
Ending balances at Sep. 30, 2019	240,580	$ 406	$ 78	448,833	(1,132)	(208,441)	$ (433)	1,269
Ending balances, shares at Sep. 30, 2019		40,624	78,286,252				98,276
Beginning balances at Jun. 30, 2019	251,103	$ 394	$ 80	454,587	(582)	(204,416)	$ (96)	1,136
Beginning balances, shares at Jun. 30, 2019		39,442	79,753,545				29,990
Vesting of restricted stock units, shares			46,450
Stock-based compensation	1,782			1,782
Common stock repurchased under share repurchase program	$ (7,875)		$ (2)	(7,536)			$ (337)
Common stock repurchased under share repurchase program, Shares	(1,582,029)		(1,513,743)				68,286
Net income (loss)	$ (3,869)					(4,013)		144
Series A convertible preferred stock dividend		$ 12				(12)
Series A convertible preferred stock dividend, shares		1,182
Foreign currency translation adjustments	(561)				(550)			(11)
Ending balances at Sep. 30, 2019	$ 240,580	$ 406	$ 78	$ 448,833	$ (1,132)	$ (208,441)	$ (433)	$ 1,269
Ending balances, shares at Sep. 30, 2019		40,624	78,286,252				98,276