CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock Series A Preferred Stock	Preferred Stock Series B Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
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		$ 225,537	$ 0	$ (131,667)
Beginning balance at Dec. 31, 2021					$ (48)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	3,299					3,299
Issuance of common stock for stock option exercises and restricted stock unit vesting, net (in shares)				277,323
Issuance of common stock for stock option exercises and restricted stock unit vesting, net	180			$ 3		177
Issuance of common stock for capital raises, net (in shares)				15,973,420
Issuance of common stock for capital raises, net	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		278,704	0	(149,686)
Ending balance at Mar. 31, 2022					(48)
Beginning balance (in shares) at Dec. 31, 2022		0	54,745	221,721,182
Beginning balance at Dec. 31, 2022	84,052	$ 0	$ 1	$ 2,217		294,874	26	(213,018)
Beginning balance at Dec. 31, 2022	48				(48)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	2,689					2,689
Issuance of common stock for stock option exercises and restricted stock unit vesting, net (in shares)				348,555
Issuance of common stock for stock option exercises and restricted stock unit vesting, net	(1)			$ 3		(4)
Issuance of common stock for capital raises, net (in shares)				4,478,956
Issuance of common stock for capital raises, net	5,559			$ 45		5,514
Other comprehensive income (loss)	(1)						(1)
Net loss	(16,498)							(16,498)
Ending balance (in shares) at Mar. 31, 2023		0	54,745	226,548,693
Ending balance at Mar. 31, 2023	75,800	$ 0	$ 1	$ 2,265		$ 303,073	$ 25	$ (229,516)
Ending balance at Mar. 31, 2023	$ 48				$ (48)