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, 2014	$ 308,509	$ 909	$ 70	$ 376,297	$ (583)	$ (68,137)	$ (96)	$ 49
Beginning balances, shares at Dec. 31, 2014		90,973	70,109,488				29,990
Vesting of restricted stock units, shares			227,382
Stock-based compensation	4,172			4,172
Common stock issued as payment for MPUs	358			358
Common stock issued as payment for MPUs, shares			54,801
Conversion of Series A convertible preferred stock to common stock	1	$ (588)	$ 1	588
Conversion of Series A convertible preferred stock to common stock, shares		(58,879)	97,935
Exercise of SARs, shares			74,036
Exercise of stock options	244			244
Exercise of stock options, shares			50,000
Series A convertible preferred stock dividend		$ 36				(36)
Series A convertible preferred stock dividend, shares		3,665
Net loss	(12,999)					(13,251)		252
Foreign currency translation adjustments	(529)				(591)			62
Ending balances at Dec. 31, 2015	299,756	$ 357	$ 71	381,659	(1,174)	(81,424)	$ (96)	363
Ending 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 employees stock purchase plan	433			433
Issuance of common stock under employees 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 employees stock purchase plan	1,183			1,183
Issuance of common stock under employees stock purchase plan, shares			129,838
Proceeds received from issuance of common stock in connection with a private offering	15,000		$ 2	14,998
Proceeds received from issuance of common stock in connection with a private offering, 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