CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIENCY) - USD ($) $ in Thousands	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock 2020 Public offering	Common Stock Common Stock Offering under the Lincoln Park Capital Registered Offering Purchase Agreement	Common Stock Lincoln Park Capital Commitment Purchase Agreement Offering Member	Common Stock	Additional Paid-in Capital 2020 Public offering	Additional Paid-in Capital Common Stock Offering under the Lincoln Park Capital Registered Offering Purchase Agreement	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	2020 Public offering	Common Stock Offering under the Lincoln Park Capital Registered Offering Purchase Agreement	Total
Balance at the beginning of the period at Dec. 31, 2018						$ 15			$ 162,393	$ 302	$ (153,535)			$ 9,175
Balance at the beginning of the period (in shares) at Dec. 31, 2018						14,703,159
Increase (Decrease) in Stockholders' Equity
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts				$ 1		$ 7		$ 999	12,115				$ 1,000	12,122
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts (in shares)				571,429	330,000	7,557,142
Issuance of common stock through ATM sales						$ 1			1,922					1,923
Issuance of common stock through ATM sales (in shares)						1,033,147
To record ATM issuance costs in Additional Paid-in Capital									(13)					(13)
To record Lincoln Park issuance costs in Additional Paid-in-Capital									(10)					(10)
Foreign currency translation adjustment										(226)				(226)
Reclassification of 2017 warrants from liability to equity									11,822		(8,374)			3,448
Dividend attributable to down round feature of warrants									359		(359)			(359)
Stock-based compensation									3,732					3,732
Net loss											(32,900)			(32,900)
Balance at the end of the period at Dec. 31, 2019						$ 24			193,319	76	(195,168)			(1,749)
Balance at the end of the period (in shares) at Dec. 31, 2019						24,194,877
Increase (Decrease) in Stockholders' Equity
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts	$ 14,062	$ 11,260	$ 24				$ 48,252					$ 48,276
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts (in shares)	1,421,801	1,137,442	23,625,000
Series A & B Convertible Preferred Stock discount - beneficial conversion feature	$ (5,226)	$ (4,173)							9,399					9,399
Series A & B Convertible Preferred Stock accrued	207	165							(372)					(372)
Conversion of Series A & B Convertible Preferred Stock dividends to prefunded warrants and common stock	(207)	(165)				$ 1			371					372
Conversion of Series A & B Convertible Preferred Stock dividends to prefunded warrants and common stock						156,713
Conversion of Series A convertible preferred stock to prefunded warrants	$ (8,836)								8,836					8,836
Conversion of Series A Convertible Preferred Stock to prefunded warrants (in shares)	(1,421,801)
Conversion of Series B Convertible Preferred Stock to common stock		$ (7,087)				$ 11			7,076					7,087
Conversion of Series B Convertible Preferred Stock to common stock (in shares)		(1,137,442)				11,374,420
Issuance of common stock upon exercise of warrants									348					348
Issuance of common stock upon exercise of warrants (in shares)						273,954
Issuance of common stock upon exercise of stock options									51					$ 51
Exercised (in shares)						32,778								32,778
Foreign currency translation adjustment										(655)				$ (655)
Dividend attributable to down round feature of warrants									303		(303)			(303)
Stock-based compensation									2,572					2,572
Net loss											(27,514)			(27,514)
Balance at the end of the period at Dec. 31, 2020						$ 60			$ 270,155	$ (579)	$ (222,985)			$ 46,651
Balance at the end of the period (in shares) at Dec. 31, 2020						59,657,742