Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Lincoln Park Capital Fund LLC [Member]	Common Stock [Member]	Common Stock [Member] Lincoln Park Capital Fund LLC [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Lincoln Park Capital Fund LLC [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2019	$ 54,545		$ 18		$ 168,746		$ (114,219)
Beginning Balance (in shares) at Dec. 31, 2019			17,834,570
Stock-based compensation	2,417				2,417
Issuance of common stock from exercise of stock options	34				34
Issuance of common stock from exercise of stock options (in shares)			18,343
Issuance of common stock from employee stock purchase plan	12				12
Issuance of common stock from employee stock purchase plan (in shares)			5,997
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	3,032		$ 1		3,031
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			687,876
Net loss	(32,758)						(32,758)
Ending Balance at Dec. 31, 2020	27,282		$ 19		174,240		(146,977)
Ending Balance (in shares) at Dec. 31, 2020			18,546,786
Stock-based compensation	2,543				2,543
Issuance of common stock from employee stock purchase plan	39				39
Issuance of common stock from employee stock purchase plan (in shares)			42,290
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	7,095		$ 3		7,092
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			2,895,518
Issuance of common stock to Lincoln Park Capital Fund		$ 375				$ 375
Issuance of common stock to Lincoln Park Capital Fund, shares				170,088
Issuance of common stock and warrants under private placement, less issuance costs	13,678		$ 4		13,674
Issuance of common stock and warrants under private placement, less issuance costs (in shares)			4,225,053
Issuance of common stock from warrant exercise	3		$ 3
Issuance of common stock from warrant exercise (in shares)			2,626,069
Net loss	(33,940)						(33,940)
Ending Balance at Dec. 31, 2021	$ 17,075		$ 29		$ 197,963		$ (180,917)
Ending Balance (in shares) at Dec. 31, 2021			28,505,804