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, 2016	$ (77,298)	$ 132	$ 580,567	$ (657,997)	$ 125,321
Balance (in shares) at Dec. 31, 2016		132,376,670			106,184
Adjustment for implementation of ASU No. 2014-09, Revenue from Contracts with Customers			122	(122)
Stock-based compensation	8,454		8,454
Issuance of restricted common stock		$ 1	(1)
Issuance of restricted common stock (in shares)		907,032
Exercise of employee stock options	$ 88	$ 1	87
Exercise of employee stock options (in shares)	180,000	59,864
Repurchase of restricted common stock	$ (2,059)	$ (1)	(2,058)
Repurchase of restricted common stock (Shares)		(394,267)
Issuance of common stock in connection with at the market offering, net	47,270	$ 10	47,260
Issuance of common stock in connection with at the market offering, net (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
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
Exercise of employee stock options	$ 242	$ 2	240
Exercise of employee stock options (in shares)	104,167	104,166
Cancelled restricted common stock	$ 1	$ (2)	3
Cancelled restricted common stock (in shares)		(271,433)
Repurchase of restricted common stock	(1,624)	$ (3)	(1,621)
Repurchase of restricted common stock (Shares)		(514,349)
Issuance of common stock in connection with at the market offering, net	47,101	$ 19	47,082
Issuance of common stock in connection with at the market offering, net (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) (in 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
Stock-based compensation	6,341		6,341
Issuance of restricted common stock	1,000	$ 2	998
Issuance of restricted common stock (in shares)		1,519,766
Exercise of employee stock options	$ 1,219		1,219
Exercise of employee stock options (in shares)	581,105	443,051
Cancelled restricted common stock (in shares)		(74,599)
Issuance of common stock upon exercise of warrants, net	$ 60,751		60,751
Repurchase of restricted common stock	(653)		(653)
Repurchase of restricted common stock (Shares)		(225,339)
Issuance of common stock in connection with at the market offering, net	$ 6,085	$ 1	6,084
Issuance of common stock in connection with at the market offering, net (in shares)	2,814,673	1,271,274
Warrant exercise, net of commissions and expenses of $1.1 million	$ 52,499	$ 18	52,481
Warrant exercise, net of commissions and expenses of $1.1 million (in shares)		17,803,031
Net loss	(117,796)			(117,796)
Balance at Dec. 31, 2019	$ 95,010	$ 182	$ 778,953	$ (684,125)
Balance (in shares) at Dec. 31, 2019		181,803,320