Note 11 - Net (Loss) Income Per Common Share - Calculation of Diluted Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net income (loss)	$ 79	$ (1,133)	$ 6,837	$ 4,795
Amount attributable to unvested restricted shares	(2)	0	(212)	(138)
Amount attributable to warrants outstanding	0	0	(4)	(335)
Net income (loss) allocated to common shareholders	$ 77	$ (1,133)	$ 6,621	$ 4,322
Weighted-average common shares issued and outstanding (in shares)	40,911,801	31,639,420	37,435,224	25,418,375
Basic earnings (loss) per common share (in dollars per share)	$ 0.00	$ (0.04)	$ 0.18	$ 0.17
Amount attributable to unvested restricted shares	$ 2	$ (0)	$ 205	$ (0)
Amount attributable to warrants	(0)	(0)	4	49
Less: gain related to change in fair value of warrants	(0)	(0)	(0)	4,467
Diluted earnings (loss) per common share	$ 77	$ (1,133)	$ 6,628	$ 279
Stock options (in shares)	1,069,207	0	1,330,207	1,754,051
Restricted shares (in shares)	1,315,462	0	1,195,154	285,975
Warrants (in shares)	0	0	24,338	1,954,137
Diluted weighted average shares issued and outstanding (in shares)	43,296,470	31,639,420	39,984,923	29,412,538
Diluted earnings (loss) per common share (in dollars per share)	$ 0.00	$ (0.04)	$ 0.17	$ 0.01