Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Public Offering [Member]	Private Offering [Member]	Inthinc [Member]	Series A Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Public Offering [Member]	Common Stock [Member] Private Offering [Member]	Common Stock [Member] Inthinc [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Public Offering [Member]	Additional Paid-in Capital [Member] Private Offering [Member]	Additional Paid-in Capital [Member] Inthinc [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Beginning balances at Dec. 31, 2016	$ 281,868				$ 364	$ 71				$ 386,920				$ (1,089)	$ (104,949)	$ (96)	$ 647
Beginning 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						555,873
Stock-based compensation	2,781									2,781
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 the acquisition of inthinc				$ 764									$ 764
Issuance of common stock in connection with the acquisition of inthinc, shares									76,796
Issuance of common stock under employee stock purchase plan	529									529
Issuance of common stock under employee stock purchase plan, shares						75,888
Payment of contingent consideration	347									347
Payment of contingent consideration, shares						40,372
Exercise of SARs, shares						105,067
Net income (loss)	(14,047)														(14,083)		36
Foreign currency translation adjustments	611													616			(5)
Ending balances at Jun. 30, 2017	287,854				$ 364	$ 74				406,339				(473)	(119,032)	$ (96)	678
Ending balances, shares at Jun. 30, 2017					36,466	73,518,654										29,990
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						490,349
Stock-based compensation	3,312									3,312
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
Issuance of common stock under employee stock purchase plan	668									668
Issuance of common stock under employee stock purchase plan, shares						81,525
Series A convertible preferred stock dividend					$ 11										(11)
Series A convertible preferred stock dividend, shares					1,128
Exercise of SARs	1					$ 1
Exercise of SARs, shares						53,272
Net income (loss)	(17,165)														(17,308)		143
Foreign currency translation adjustments	(402)													(397)			(5)
Ending balances at Jun. 30, 2018	$ 261,605				$ 387	$ 79				$ 444,069				$ (141)	$ (183,564)	$ (96)	$ 871
Ending balances, shares at Jun. 30, 2018					38,672	78,593,002										29,990