Note 6 - Earnings (Loss) Per Share - Computation of Basic and Diluted Net Income (Loss) per Share (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 loss	$ (15,797)	$ (9,616)	$ (39,622)	$ (45,013)
Basic (in shares)	27,097,372	22,744,361	26,791,415	21,275,778
Diluted (in shares)	27,097,372	22,744,361	26,791,415	21,275,778
Basic (in dollars per share)	$ (0.58)	$ (0.42)	$ (1.48)	$ (2.12)
Diluted (in dollars per share)	$ (0.58)	$ (0.42)	$ (1.48)	$ (2.12)