STATEMENTS OF CHANGES IN PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital Common Stock	Accumulated Deficit	Series 1 Preferred Stock - Mezzanine
Balance at Dec. 31, 2015	$ 87,371	$ 132	$ 579,939	$ (492,700)
Balance (in shares) at Dec. 31, 2015		131,718,579
Exercise of employee stock options	$ 714	$ 2	712
Exercise of employee stock options (in shares)	234,833	189,696
Stock-based compensation	$ 8,452		8,452
Issuance of restricted common stock		$ 712	(712)
Issuance of restricted common stock (in shares)		711,770
Issuance of common stock in a license agreement	87		87		$ 118,242
Issuance of common stock in a license agreement (in shares)					100,000
Repurchase of restricted common stock	(1,500)	$ (2)	(1,498)
Repurchase of restricted common stock (in shares)		(243,207)
Stock buy-back	(2)		(2)
Stock buy-back (Shares)		(168)
Preferred stock dividends					$ 7,079
Preferred stock dividends	(7,123)		(7,123)
Preferred stock dividends (in shares)					6,184
Net loss	(165,297)			(165,297)
Balance at Dec. 31, 2016	(77,298)	$ 132	580,567	(657,997)	$ 125,321
Balance (in shares) at Dec. 31, 2016		132,376,670			106,184
Exercise of employee stock options	$ 88	$ 1	87
Exercise of employee stock options (in shares)	180,000	59,864
Stock-based compensation	$ 8,454		8,454
Issuance of restricted common stock		$ 1	(1)
Issuance of restricted common stock (in shares)		907,032
Repurchase of restricted common stock	(2,059)	$ (1)	(2,058)
Repurchase of restricted common stock (in shares)		(394,267)
Issuance of common stock, net of commissions and expenses	47,270	$ 10	47,260
Issuance of common stock, net of commissions and expenses (in shares)		9,708,738
Preferred stock dividends					$ 18,672
Preferred stock dividends	(18,938)		(18,938)
Preferred stock dividends (in shares)					13,460
Net loss	(54,323)			(54,323)
Balance at Dec. 31, 2017	(96,806)	$ 143	615,493	(712,442)	$ 143,993
Balance (in shares) at Dec. 31, 2017		142,658,037			119,644
Cumulative effect adjustment ASU No. 2016-09			122	(122)
Exercise of employee stock options	$ 242	$ 2	240
Exercise of employee stock options (in shares)	104,167	104,166
Adjustment for implementation of ASU No. 2014-09, Revenue from Contracts with Customers	$ (8,131)			(8,131)
Stock-based compensation	7,534		7,534
Issuance of restricted common stock	1	$ 2	(1)
Issuance of restricted common stock (in shares)		150,321
Cancelled restricted common stock	1	$ (2)	3
Cancelled restricted common stock (Shares)		(271,433)
Repurchase of restricted common stock	(1,624)	$ (3)	(1,621)
Repurchase of restricted common stock (in shares)		(514,349)
Issuance of common stock, net of commissions and expenses	47,101	$ 19	47,082
Issuance of common stock, net of commissions and expenses (in shares)		18,939,394
Preferred stock dividends					$ 16,775
Preferred stock dividends	(16,998)		(16,998)
Preferred stock dividends (in shares)					11,415
Settlement of a related party relationship (Note 7)	207,361			207,361	$ (160,767)
Settlement of a related party relationship (Note 7) (Shares)					(131,059)
Net loss	(53,117)			(53,117)
Balance at Dec. 31, 2018	$ 85,564	$ 161	$ 651,732	$ (566,329)
Balance (in shares) at Dec. 31, 2018		161,066,136