CONSOLIDATED STATEMENTS OF STOCKHOLDERS' (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit
Balance, beginning of period (in shares) at Dec. 31, 2017		112,703,926		3,356,409
Balance, beginning of period at Dec. 31, 2017	$ 73,797	$ 113	$ 164,649	$ (44,384)	$ (46,581)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	14,768		14,768
Exercise of stock options	3,555		(8,210)	$ 11,765
Exercise of stock options (in shares)				(786,708)
Issuance of restricted stock	0		(25,657)	$ 25,657
Issuance of restricted stock (in shares)				(1,947,475)
Restricted stock cancellation / forfeited	$ 0		19,194	$ (19,194)
Restricted stock cancellation/forfeited (in shares)				1,861,314
Shares repurchased (in shares)	507,600			507,600
Shares repurchased	$ (7,572)			$ (7,572)
Shares repurchased for tax withholding on vesting of restricted stock units (in shares)				614,123
Shares repurchased for tax withholding on vesting of restricted stock units	(4,914)			$ (4,914)
Net loss	(29,979)				(29,979)
Balance, end of period (in shares) at Dec. 31, 2018		112,703,926		3,605,263
Balance, end of period at Dec. 31, 2018	49,655	$ 113	164,744	$ (38,642)	(76,560)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	11,689		11,689
Exercise of stock options	108		(1,343)	$ 1,451
Exercise of stock options (in shares)				(150,000)
Issuance of restricted stock	0		(37,798)	$ 37,798
Issuance of restricted stock (in shares)				(3,084,875)
Restricted stock cancellation / forfeited	0		9,939	$ (9,939)
Restricted stock cancellation/forfeited (in shares)				1,084,971
Shares repurchased for tax withholding on vesting of restricted stock units (in shares)				429,918
Shares repurchased for tax withholding on vesting of restricted stock units	(1,474)			$ (1,474)
Net loss	(25,580)				(25,580)
Balance, end of period (in shares) at Dec. 31, 2019		112,703,926		1,885,277
Balance, end of period at Dec. 31, 2019	34,398	$ 113	147,231	$ (10,806)	(102,140)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Series B Convertible Preferred Stock	32,954		32,954
Deemed dividends	(32,028)		(32,028)
Share-based compensation expense	15,733		15,733
Exercise of stock options	$ 411		(3,180)	$ 3,591
Exercise of stock options (in shares)	(508,300)			(359,328)
Issuance of restricted stock	$ 0		(5,463)	$ 5,463
Issuance of restricted stock (in shares)				(613,146)
Restricted stock cancellation / forfeited	$ 0		3,363	$ (3,363)
Restricted stock cancellation/forfeited (in shares)				425,388
Shares repurchased (in shares)	148,972
Shares repurchased for tax withholding on vesting of restricted stock units (in shares)				435,492
Shares repurchased for tax withholding on vesting of restricted stock units	$ (2,334)			$ (2,334)
Net loss	(49,284)				(49,284)
Balance, end of period (in shares) at Dec. 31, 2020		112,703,926		1,773,683
Balance, end of period at Dec. 31, 2020	$ (150)	$ 113	$ 158,610	$ (7,449)	$ (151,424)