Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	ATM Program [Member] Common Stock [Member]	ATM Program [Member] Additional Paid-in Capital [Member]	ATM Program [Member] Retained Earnings [Member]	ATM Program [Member] Treasury Stock [Member]	ATM Program [Member]	Share Purchase Agreement, December 2019 [Member] Common Stock [Member]	Share Purchase Agreement, December 2019 [Member] Additional Paid-in Capital [Member]	Share Purchase Agreement, December 2019 [Member] Retained Earnings [Member]	Share Purchase Agreement, December 2019 [Member] Treasury Stock [Member]	Share Purchase Agreement, December 2019 [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2020											16,922
Balance at Dec. 31, 2020											$ 17	$ 790,277	$ (717,688)	$ (3,054)	$ 69,552
Net loss													(8,961)		(8,961)
Issuance of common stock and common stock warrants, net of issuance costs (in shares)											9,230
Issuance of common stock and common stock warrants, net of issuance costs											$ 9	27,381			27,390
Stock-based compensation expense												2,443			2,443
Issuance of common stock, ATM Program, net of issuance costs (in shares)	105
Issuance of common stock, ATM Program, net of issuance costs	$ 0	$ 570			$ 570
Issuance of common stock warrants, equity consideration for service agreement							$ 494			$ 494
Balance (in shares) at Mar. 31, 2021											26,257
Balance at Mar. 31, 2021											$ 26	821,165	(726,649)	(3,054)	91,488
Balance (in shares) at Dec. 31, 2021											28,269
Balance at Dec. 31, 2021											$ 28	830,231	(785,324)	(3,054)	41,881
Net loss													(8,127)		(8,127)
Stock-based compensation expense												770			770
Issuance of common stock, ATM Program, net of issuance costs (in shares)	200
Issuance of common stock, ATM Program, net of issuance costs	$ 0	$ 205			$ 205
Balance (in shares) at Mar. 31, 2022											28,469
Balance at Mar. 31, 2022											$ 28	$ 831,206	$ (793,451)	$ (3,054)	$ 34,729