Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series D Preferred Stock [Member]	Series E Preferred Stock [Member]	Series E1 Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series D Warrants	Preferred Stock [Member]	Preferred Stock [Member] Series D Preferred Stock [Member]	Preferred Stock [Member] Series E Preferred Stock [Member]	Preferred Stock [Member] Series E1 Preferred Stock [Member]	Additional Paid in Capital [Member]	Additional Paid in Capital [Member] Series D Preferred Stock [Member]	Additional Paid in Capital [Member] Series E Preferred Stock [Member]	Additional Paid in Capital [Member] Series E1 Preferred Stock [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Series E Preferred Stock [Member]	Accumulated Deficit [Member] Series E1 Preferred Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2018	$ (14,939)										$ 329,065				$ (344,054)			$ 50
Balance (in shares) at Dec. 31, 2018					14,715		101
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	273										273
Compensation expense for issuance of restricted stock	$ 4										4
Compensation expense for issuance of restricted stock (in shares)	20				20
Issuance of Preferred Stock		$ 150	$ 29,536	$ 9,510								$ 150	$ 42,876	$ 14,408		$ (13,340)	$ (4,898)
Issuance of Preferred Stock (in shares)								15	32,572	9,510
Retirement of Series D Preferred Stock		$ (1,160)										$ (1,160)
Retirement of Series D Preferred Stock (in Shares)								(116)
Exercise of pre-funded warrants (in shares)	11,285					11,285
Exchange of warrants	$ 13										13
Exchange of warrants (in shares)					92
Fair value of warrants issued	(20,844)										(20,844)
Conversion of preferred stock into common stock	1										1
Conversion of Preferred stock into common stock (in shares)					13,455		(565)
Fractional rounding related to reverse stock split					$ 1						(1)
Fractional rounding related to reverse stock split (in shares)					27,524
Net loss	(8,879)														(8,879)
Comprehensive loss	(22)																	(22)
Balance at Dec. 31, 2019	(6,357)				$ 1						364,785				(371,171)			28
Balance (in shares) at Dec. 31, 2019					67,091		41,517
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	$ 3,505										3,505
Compensation expense for issuance of restricted stock (in shares)	72,976
Shares settled for services	$ 406				$ 1						405
Shares settled for services (in shares)					50,013
Shares settled for accrued compensation	$ 230										230
Shares settled for accrued compensation (in shares)					22,963
Exercise of pre-funded warrants (in shares)	6,000
Conversion of preferred stock into common stock	$ (1)				$ 20						(21)
Conversion of Preferred stock into common stock (in shares)					2,084,507		(20,887)
Registration costs of Series E and Series E-1 Preferred Stock and related warrants	(106)										(106)
Fair value of warrants reclassified from liability to equity	6,200										6,200
Exercise of warrants into common stock	1,858				$ 2						1,856
Exercise of warrants into common stock (in shares)					191,803
Public Offering - issuance of common stock and warrants	19,378				$ 18						19,360
Public Offering - issuance of common stock and warrants (in shares)					1,823,000
ATM Offering	866				$ 1						865
ATM Offering, Shares					77,644
Confidentially Marketed Public Offering - issuance of common stock	20,387				$ 17						20,370
Confidentially Marketed Public Offering - issuance of common stock (in shares)					1,679,031
Fractional rounding related to reverse stock split (in shares)					49		1
Net loss	(24,156)														(24,156)
Comprehensive loss	(132)																	(132)
Balance at Dec. 31, 2020	$ 22,078				$ 60						$ 417,449				$ (395,327)			$ (104)
Balance (in shares) at Dec. 31, 2020					5,996,101		20,631