Consolidated Statements of Changes in Equity - 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, 2015	$ 299,756	$ 357	$ 71	$ 381,659	$ (1,174)	$ (81,424)	$ (96)	$ 363
Beginning balances, shares at Dec. 31, 2015		35,759	70,613,642				29,990
Vesting of restricted stock units, shares			262,474
Stock-based compensation	4,469			4,469
Payment of contingent consideration	352			352
Payment of contingent consideration, shares			35,464
Issuance of common stock under employee stock purchase plan	433			433
Issuance of common stock under employee stock purchase plan, shares			48,208
Conversion of Series A convertible preferred stock to common stock		$ (7)		7
Conversion of Series A convertible preferred stock to common stock, shares		(708)	1,178
Exercise of SARs, shares			150,897
Series A convertible preferred stock dividend		$ 14				(14)
Series A convertible preferred stock dividend, shares		1,415
Net loss	(23,226)					(23,511)		285
Foreign currency translation adjustments	84				85			(1)
Ending balances at Dec. 31, 2016	281,868	$ 364	$ 71	386,920	(1,089)	(104,949)	$ (96)	647
Ending balances, shares at Dec. 31, 2016		36,466	71,111,863				29,990
Vesting of restricted stock units	1		$ 1
Vesting of restricted stock units, shares			584,261
Stock-based compensation	5,086			5,086
Payment of contingent consideration	347			347
Payment of contingent consideration, shares			40,372
Issuance of common stock under employee stock purchase plan	1,183			1,183
Issuance of common stock under employee stock purchase plan, shares			129,838
Proceeds from offering of common stock	15,000		$ 2	14,998
Proceeds from offering of common stock, shares			1,552,795
Issuance of common stock in connection with acquisitions	2,764			2,764
Issuance of common stock in connection with acquisitions, shares			267,818
Exercise of SARs, shares			749,632
Series A convertible preferred stock dividend		$ 12				(12)
Series A convertible preferred stock dividend, shares		1,078
Net loss	(61,195)					(61,284)		89
Foreign currency translation adjustments	1,342				1,345			(3)
Ending balances at Dec. 31, 2017	246,396	$ 376	$ 74	411,298	256	(166,245)	$ (96)	733
Ending 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			581,013
Stock-based compensation	8,060			8,060
Issuance of common stock under employee stock purchase plan	1,194			1,194
Issuance of common stock under employee stock purchase plan, shares			152,965
Proceeds from offering of common stock	27,967		$ 3	27,964
Proceeds from offering of common stock, shares			3,450,000
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			306,409
Series A convertible preferred stock dividend		$ 18				(18)
Series A convertible preferred stock dividend, shares		1,898
Net loss	(25,939)					(26,244)		305
Foreign currency translation adjustments	(649)				(637)			(12)
Ending balances at Dec. 31, 2018	$ 257,858	$ 394	$ 79	$ 449,343	$ (381)	$ (192,507)	$ (96)	$ 1,026
Ending balances, shares at Dec. 31, 2018		39,442	79,008,243				29,990