Condensed Consolidated Statements of Stockholders' Equity / (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ (4,058)	$ 3	$ 7	$ (24)	$ 469,877	$ (473,921)
Beginning balance (shares) at Dec. 31, 2017		2,750,000,000	7,007,782,000	7,854,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,029				1,029
Restricted shares vested			30,000,000
Issuance of common stock as a result of Employee Stock Purchase Program	137				137
Issuance of common stock as a result of Employee Stock Purchase Program (shares)			55,087,000
Net loss	(11,574)					(11,574)
Ending balance at Mar. 31, 2018	(14,487)	$ 3	$ 7	$ (24)	471,043	(485,516)
Ending balance (shares) at Mar. 31, 2018		2,750,000,000	7,092,869,000	7,854,000
Beginning balance at Dec. 31, 2018	14,289	$ 3	$ 100	$ (24)	534,081	(519,871)
Beginning balance (shares) at Dec. 31, 2018		2,750,000	99,948,437	7,854
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,069				1,069
Issuance of common stock through the sales agreement, net of fees	773		$ 2		771
Issuance of common stock through the ATM agreement, net of fees (shares)			2,182,350
Issuance of common stock with exercise of Series B Warrants	20				20
Issuance of common stock through exercise of Series B Warrants, net of fees (shares)			41,923
Net loss	(14,684)					(14,684)
Ending balance at Mar. 31, 2019	$ 1,467	$ 3	$ 102	$ (24)	$ 535,941	$ (534,555)
Ending balance (shares) at Mar. 31, 2019		2,750,000	102,172,710	7,854