Note 10 - Net Income (Loss) Per Common Share - Calculation of Diluted Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income (loss)	$ (1,133)	$ 10,269	$ 4,795	$ (4,640)
Amount attributable to unvested restricted shares	0	(207)	(138)	0
Amount attributable to warrants outstanding	0	(1,682)	(335)	0
Net income (loss) allocated to common shareholders	$ (1,133)	$ 8,380	$ 4,322	$ (4,640)
Basic (in shares)	31,639,420	19,735,364	25,418,375	19,071,722
Basic earnings (loss) per common share (in dollars per share)	$ (0.04)	$ 0.42	$ 0.17	$ (0.24)
Amount attributable to non-participating warrants	$ (0)	$ 279	$ 49	$ (0)
Less: gain related to change in fair value of warrants	(0)	1,128	4,467	(0)
Diluted net income (loss) allocated to common shareholders	$ (1,133)	$ 8,862	$ 279	$ (4,640)
Warrants (in shares)	0	3,046,363	1,954,137	0
Diluted weighted-average shares issued and outstanding (in shares)	31,639,420	25,343,112	29,412,538	19,071,722
Diluted earnings (loss) per common share (in dollars per share)	$ (0.04)	$ 0.35	$ 0.01	$ (0.24)
Share-based Payment Arrangement, Option [Member]
Share-based payment arrangements (in shares)	0	2,420,884	1,754,051	0
Restricted Stock [Member]
Share-based payment arrangements (in shares)	0	140,501	285,975	0