CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series B Preferred Stock	At-the-market Issuance	Registered Direct Offering	Preferred Stock Series A Preferred Stock	Preferred Stock Series B Preferred Stock	Common Stock	Common Stock At-the-market Issuance	Common Stock Registered Direct Offering	Treasury Stock	Additional Paid-in Capital	Additional Paid-in Capital Series B Preferred Stock	Additional Paid-in Capital At-the-market Issuance	Additional Paid-in Capital Registered Direct Offering	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020					7	0	184,133,384
Beginning balance at Dec. 31, 2020	$ 21,550				$ 0	$ 0	$ 1,841			$ (48)	$ 93,059				$ (73,302)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	833										833
Issuance of common stock for option exercises (in shares)							157,468
Issuance of common stock for option exercises	176						$ 2				174
Issuance of stock (in shares)						54,745		987,000	3,000,000
Issuance of stock		$ 4,954	$ 4,849	$ 21,204		$ 1		$ 10	$ 30			$ 4,953	$ 4,839	$ 21,174
Net loss	(7,077)														(7,077)
Ending balance (in shares) at Mar. 31, 2021					7	54,745	188,277,852
Ending balance at Mar. 31, 2021	46,489				$ 0	$ 1	$ 1,883			(48)	125,032				(80,379)
Beginning balance (in shares) at Dec. 31, 2021					7	54,745	199,502,183
Beginning balance at Dec. 31, 2021	95,818				$ 0	$ 1	$ 1,995			(48)	225,537				(131,667)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	$ 3,299										3,299
Issuance of common stock for option exercises (in shares)	277,323						277,323
Issuance of common stock for option exercises	$ 180						$ 3				177
Issuance of stock (in shares)							15,973,420
Issuance of stock	49,851						$ 160				49,691
Net loss	(18,019)														(18,019)
Ending balance (in shares) at Mar. 31, 2022					7	54,745	215,752,926
Ending balance at Mar. 31, 2022	$ 131,129				$ 0	$ 1	$ 2,158			$ (48)	$ 278,704				$ (149,686)