Note 1 - Organization and Significant Accounting Policies - Calculation of Diluted Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net (loss) income	$ (7,635)	$ 2,667	$ (1,657)
Amount attributable to unvested restricted shares	0	(135)	0
Amount attributable to warrants outstanding	0	(82)	0
Net (loss) income allocated to common shareholders	$ (7,635)	$ 2,450	$ (1,657)
Weighted-average common shares issued and outstanding (in shares)	38,503,944	27,306,258	19,460,299
Basic (loss) earnings per common share (in dollars per share)	$ (0.20)	$ 0.09	$ (0.09)
Amount attributable to warrants	$ 0	$ (20)	$ 0
Less: gain related to change in fair value of warrants	0	(3,601)	0
Diluted (loss) earnings per common share	$ (7,635)	$ (954)	$ (1,657)
Diluted (loss) earnings per common share (in dollars per share)	$ (0.20)	$ (0.03)	$ (0.09)