Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Private Placement [Member] Common Stock [Member]	Private Placement [Member] Additional Paid-in Capital [Member]	Private Placement [Member] Retained Earnings [Member]	Private Placement [Member]	Direct Offering [Member] Common Stock [Member]	Direct Offering [Member] Additional Paid-in Capital [Member]	Direct Offering [Member] Retained Earnings [Member]	Direct Offering [Member]	At-the-market Offering [Member] Common Stock [Member]	At-the-market Offering [Member] Additional Paid-in Capital [Member]	At-the-market Offering [Member] Retained Earnings [Member]	At-the-market Offering [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2019													15,001,795
Balance at Dec. 31, 2019													$ 2	$ 539,158	$ (470,111)	$ 69,049
Issuance of common stock upon exercise of options (in shares)													114,515
Issuance of common stock upon exercise of options													$ 0	315	0	315
Issuance of common stock under employee benefit plans (in shares)													56,291
Issuance of common stock under employee benefit plans													$ 0	80	0	80
Issuance of common stock, net (in shares)	931,098				377,400
Issuance of common stock, net	$ 0	$ 4,922	$ 0	$ 4,922	$ 0	$ 2,266	$ 0	$ 2,266
Stock-based compensation													0	1,966	0	1,966
Net loss													$ 0	0	(30,543)	(30,543)
Balances (in shares) at Dec. 31, 2020													16,481,099
Balances at Dec. 31, 2020													$ 2	548,707	(500,654)	$ 48,055
Issuance of common stock upon exercise of options (in shares)													219,109			219,063
Issuance of common stock upon exercise of options													$ 0	308	0	$ 308
Issuance of common stock under employee benefit plans (in shares)													31,759
Issuance of common stock under employee benefit plans													$ 0	120	0	120
Issuance of common stock, net (in shares)									1,432,627				2,875,000
Issuance of common stock, net					$ 0	$ 20,866	$ 0	$ 20,866	$ 0	$ 9,767	$ 0	$ 9,767
Stock-based compensation													$ 0	2,257	0	2,257
Net loss													$ 0	0	(39,151)	(39,151)
Balances (in shares) at Dec. 31, 2021													21,039,594
Balances at Dec. 31, 2021													$ 2	$ 582,025	$ (539,805)	$ 42,222