Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Stock Units Issued (SUI) [Member] Preferred Stock [Member]	Stock Units Issued (SUI) [Member] Common Stock [Member]	Stock Units Issued (SUI) [Member] Retained Earnings [Member]	Stock Units Issued (SUI) [Member]	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2020					225	4,523,809
Balance at Dec. 31, 2020					$ 112	$ 322,218	$ (298,910)	$ 23,420
Sales of common stock, net of costs (in shares)						306,240
Sales of common stock, net of costs					$ 0	$ 2,721	0	2,721
Common stock awards under equity incentive plans (in shares)					0	70,858
Common stock awards under equity incentive plans					$ 0	$ 1,114	0	1,114
Exercise of common stock warrants (in shares)					0	248,543
Exercise of common stock warrants					$ 0	$ 171	0	171
Common stock issued to vendors (in shares)					0	2,400
Common stock issued to vendors					$ 0	$ 18	0	18
Conversion of preferred stock into common stock (in shares)					(75)	7,117
Conversion of preferred stock into common stock					$ (37)	$ 37	0	0
Net loss					$ 0	$ 0	(8,949)	(8,949)
Balance (in shares) at Dec. 31, 2021					150	5,158,967
Balance at Dec. 31, 2021					$ 75	$ 326,279	(307,859)	18,495
Common stock awards under equity incentive plans (in shares)					0	137,695
Common stock awards under equity incentive plans					$ 0	$ 1,261	0	1,261
Exercise of common stock warrants (in shares)					0	325,000
Exercise of common stock warrants					$ 0	$ 0	0	0
Common stock issued to vendors (in shares)	0	0			0	2,400
Common stock issued to vendors	$ 0	$ 15	$ 0	$ 15	$ 0	$ 10	0	10
Net loss					$ 0	$ 0	(7,858)	(7,858)
Sales of common stock and common stock warrants, net of costs (in shares)					0	675,000
Sales of common stock and common stock warrants, net of costs					$ 0	$ 986	0	986
Other (in shares)					0	10,447
Balance (in shares) at Dec. 31, 2022					150	6,309,509
Balance at Dec. 31, 2022					$ 75	$ 328,551	$ (315,717)	$ 12,909