Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Nov. 10, 2014	Jan. 17, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 20, 2016	Feb. 17, 2016
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance			17,402,425
Shares of common stock issued in public offering	14,785,714	6,325,000
Public offering price per share	$ 5.60	$ 6.15
Net proceeds received from shares issuances	$ 78,131	$ 36,607			$ 114,738
Underwriters' Overallotment Option [Member]
Class Of Stock [Line Items]
Shares of common stock issued in public offering	1,928,571	825,000
Prior to the Approval of 2016 LTIP and ESPP [Member]
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance			7,451,870
2016 LTIP [Member]
Class Of Stock [Line Items]
Number of shares authorized under the plan						6,949,400	6,949,400
2006 LTIP [Member]
Class Of Stock [Line Items]
Number of shares authorized under the plan							1,949,400
ESPP [Member]
Class Of Stock [Line Items]
Number of shares authorized under the plan						5,000,000
Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, shares authorized			1,000,000	1,000,000
Preferred Stock, shares issued			36,466	35,759
Preferred Stock, shares outstanding			36,466	35,759
Preferred stock dividend percentage received			4.00%
Preferred stock redemption price paid			$ 10.00
Preferred stock dividends issued			1,415	3,665
Dividends in arrears			$ 4
Preferred stock convertible into common stock			1.66611
Preferred Stock, par value			$ 0.001	$ 0.001
Preferred stock voting rights			Each share of the Series A convertible preferred stock is entitled to one vote for each share of common stock into which the preferred stock is convertible.
Preference of preferred stock			$ 10.00
Preferred stock redemption period			Two years
Series A Convertible Preferred Stock [Member] | Minimum [Member]
Class Of Stock [Line Items]
Preferred Stock, par value			$ 11.20
Series A Convertible Preferred Stock [Member] | StarTrak [Member]
Class Of Stock [Line Items]
Preferred Stock, shares issued			183,550
Preferred Stock, shares outstanding			36,466
Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, shares authorized			50,000,000