Condensed Consolidated Statement of Stockholders' Equity - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Series A Preferred Stock [Member]	Series B Preferred Stock [Member]
Beginning Balance at Dec. 31, 2017	$ 8,877	$ 56	$ 313,922	$ (47)	$ (305,056)	$ 2
Beginning Balance, shares at Dec. 31, 2017		55,904,072				2,093,155
Stock-based compensation	$ 4,004		$ 4,004
Stock-based compensation, Shares	0	0	0	0	0	0	0
Stock option exercises	$ 306		$ 306
Stock option exercises, shares	196,541	169,016
Restricted stock awards		$ 1	(1)
Restricted stock awards, shares		1,266,433
Common stock issuance upon retirement		$ 2	(2)
Common stock issuance upon retirement, shares	2,119,925	2,119,925
Series B issuance, net of issuance costs	$ 47,894		47,894
Series B issuance, net of issuance costs, shares							5,000
Cumulative effect of accounting change	135				$ 135
Net loss	(20,479)				(20,479)
Ending Balance at Jun. 30, 2018	$ 40,737	$ 59	$ 366,123	$ (47)	$ (325,400)	$ 2
Ending Balance, shares at Jun. 30, 2018		59,459,446				2,093,155	5,000