CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Follow-on Public Offering, One Common Stock	Follow-on Public Offering, One Additional Paid-in Capital	Follow-on Public Offering, One	Follow-on Public Offering, Two Common Stock	Follow-on Public Offering, Two Additional Paid-in Capital	Follow-on Public Offering, Two	Series A Preferred Stock Preferred Stock	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Total
Balance at Dec. 31, 2019								$ 22	$ 295,121		$ (235,574)	$ 59,569
Balance (in shares) at Dec. 31, 2019								21,617,781		7,307
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation expense									7,642			7,642
Exercise of stock options									1,020			1,020
Exercise of stock options (in shares)								198,475
Issuance of restricted stock (in shares)								33,997
Deemed dividend on beneficial conversion feature - Series A convertible preferred stock									8,880		(8,880)
Issuance of common stock	$ 5	$ 42,956	$ 42,961	$ 5	$ 64,787	$ 64,792
Issuance of common stock (in shares)	4,600,000			5,000,000
Issuance of common stock under equity distribution agreement									489			489
Issuance of common stock under equity distribution agreement (in shares)								78,807
Transfer of convertible preferred stock into permanent equity							$ 8,745					8,745
Transfer of convertible preferred stock into permanent equity (in shares)							9,303
Conversion of convertible preferred stock to common stock							$ (4,276)	$ 5	23,727			19,456
Conversion of convertible preferred stock to common stock (in shares)							(4,550)	5,049,400
Net loss											(67,475)	(67,475)
Balance at Dec. 31, 2020							$ 4,469	$ 37	444,622		(311,929)	137,199
Balance (in shares) at Dec. 31, 2020							4,753	36,578,460		7,307
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation expense									13,867			13,867
Exercise of stock options									1,199			1,199
Exercise of stock options (in shares)								176,194
Financing costs									(3)			(3)
Conversion of convertible preferred stock to common stock							$ (167)		167
Conversion of convertible preferred stock to common stock (in shares)							(178)	35,600
Net loss											(98,776)	(98,776)
Balance at Dec. 31, 2021							$ 4,302	$ 37	$ 459,852		$ (410,705)	$ 53,486
Balance (in shares) at Dec. 31, 2021							4,575	36,790,254		7,307