Consolidated Statements of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit	Series A Preferred Stock	Series B Preferred Stock	Series B Preferred Stock Common Stock	Series B Preferred Stock Additional Paid-In Capital	Series B Preferred Stock Accumulated Deficit
Beginning balance, preferred stock (in shares) at Dec. 31, 2017						2,093,155	0
Beginning balance, common stock (in shares) at Dec. 31, 2017		55,904,072
Beginning Balance at Dec. 31, 2017	$ 8,877	$ 56	$ 313,922	$ (47)	$ (305,056)	$ 2	$ 0
Stock-based compensation	$ 5,941		5,941
Stock option exercises (in shares)	350,441	350,441
Stock option exercises	$ 670		670
Restricted stock awards (in shares)		1,733,731
Restricted stock awards		$ 2	(2)
Common stock issuance upon retirement (in shares)		2,249,925
Common stock issuance upon retirement		$ 2	(2)
Series B issuance, net of issuance costs (in shares)							5,000
Series B issuance, net of issuance costs							$ 47,986		$ 47,986
Conversion of convertible securities (in shares)							1,900	(10,555,556)
Conversion of convertible securities								$ 11	(11)
Series B beneficial conversion feature	(12,500)		(12,500)						12,500	$ (12,500)
Cumulative effect of accounting change	135				135
Net income (loss)	(33,867)				(33,867)
Ending balance, preferred stock (in shares) at Dec. 31, 2018						2,093,155	3,100
Ending balance, common stock (in shares) at Dec. 31, 2018		70,793,725
Ending Balance at Dec. 31, 2018	29,742	$ 71	381,004	(47)	(351,288)	$ 2	$ 0
Stock-based compensation	$ 5,418		5,418
Stock option exercises (in shares)	799,800	799,800
Stock option exercises	$ 2,319		2,319
Restricted stock awards (in shares)		806,661
Restricted stock awards		$ 1	(1)
Conversion of convertible securities (in shares)							2,482	(13,788,888)
Conversion of convertible securities								$ 14	(14)
Equity offering, net of finance costs (in shares)		10,000,000
Equity offering, net of finance costs	47,590	$ 10	47,580
Net income (loss)	$ (15,305)				(15,305)
Ending balance, preferred stock (in shares) at Dec. 31, 2019						2,093,155	618
Ending balance, common stock (in shares) at Dec. 31, 2019	96,173,583	96,189,074
Ending Balance at Dec. 31, 2019	$ 69,764	$ 96	436,306	(47)	(366,593)	$ 2	$ 0
Stock-based compensation	$ 9,595		9,595
Stock option exercises (in shares)	1,400,003	1,400,003
Stock option exercises	$ 3,370	$ 1	3,369
Restricted stock awards (in shares)		762,987
Restricted stock awards		$ 4	(4)
Conversion of convertible securities (in shares)		(972,222)				2,093,155	(175)	(3,065,377)
Conversion of convertible securities						$ (2)	$ 1	$ 3	$ (2)
Share repurchase	(205)			(205)
Net income (loss)	$ 25,711				25,711
Ending balance, preferred stock (in shares) at Dec. 31, 2020						0	443
Ending balance, common stock (in shares) at Dec. 31, 2020	101,354,447	101,417,441
Ending Balance at Dec. 31, 2020	$ 108,234	$ 104	$ 449,264	$ (252)	$ (340,882)	$ 0	$ 0