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, 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			567,682
Stock-based compensation	4,138			4,138
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
Exercise of SARs, shares			3,032
Net income (loss)	(11,782)					(11,909)		127
Foreign currency translation adjustments	(218)				(201)			(17)
Ending balances at Jun. 30, 2019	251,103	$ 394	$ 80	454,587	(582)	(204,416)	$ (96)	1,136
Ending balances, shares at Jun. 30, 2019		39,442	79,753,545				29,990
Beginning balances at Mar. 31, 2019	254,845	$ 394	$ 80	452,240	(887)	(197,997)	$ (96)	1,111
Beginning balances, shares at Mar. 31, 2019		39,442	79,568,496				29,990
Vesting of restricted stock units, shares			71,346
Stock-based compensation	1,743			1,743
Issuance of common stock under employee stock purchase plan	604			604
Issuance of common stock under employee stock purchase plan, shares			113,703
Net income (loss)	(6,386)					(6,419)		33
Foreign currency translation adjustments	297				305			(8)
Ending balances at Jun. 30, 2019	251,103	$ 394	$ 80	454,587	(582)	(204,416)	$ (96)	1,136
Ending balances, shares at Jun. 30, 2019		39,442	79,753,545				29,990
Beginning balances at Dec. 31, 2019	237,516	$ 406	$ 78	447,681	(1,013)	(210,942)		1,306
Beginning balances, shares at Dec. 31, 2019		40,624	78,062,451
Vesting of restricted stock units	1		$ 1
Vesting of restricted stock units, shares			519,660
Stock-based compensation	3,323			3,323
Issuance of common stock under employee stock purchase plan	430			430
Issuance of common stock under employee stock purchase plan, shares			166,580
Common stock repurchased and retired under share repurchase program	$ (2,527)		$ (1)	(2,526)
Common stock repurchased and retired under share repurchase program, Shares	(836,904)		(836,904)
Exercise of SARs, shares			41,091
Net income (loss)	$ (13,478)					(13,645)		167
Foreign currency translation adjustments	308				337			(29)
Ending balances at Jun. 30, 2020	225,573	$ 406	$ 78	448,908	(676)	(224,587)		1,444
Ending balances, shares at Jun. 30, 2020		40,624	77,952,878
Beginning balances at Mar. 31, 2020	229,990	$ 406	$ 78	449,431	(907)	(217,917)	$ (2,502)	1,401
Beginning balances, shares at Mar. 31, 2020		40,624	78,525,184				836,904
Vesting of restricted stock units, shares			98,018
Stock-based compensation	1,549			1,549
Issuance of common stock under employee stock purchase plan	430			430
Issuance of common stock under employee stock purchase plan, shares			166,580
Common stock repurchased and retired under share repurchase program				(2,502)			$ 2,502
Common stock repurchased and retired under share repurchase program, Shares			(836,904)				(836,904)
Net income (loss)	(6,641)					(6,670)		29
Foreign currency translation adjustments	245				231			14
Ending balances at Jun. 30, 2020	$ 225,573	$ 406	$ 78	$ 448,908	$ (676)	$ (224,587)		$ 1,444
Ending balances, shares at Jun. 30, 2020		40,624	77,952,878