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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net loss	$ (9,616)	$ (8,780)	$ (45,013)	$ (30,620)
Basic (in shares)	22,744,361	20,022,520	21,275,778	19,939,605
Diluted (in shares)	22,744,361	20,022,520	21,275,778	19,939,605
Basic (in dollars per share)	$ (0.42)	$ (0.44)	$ (2.12)	$ (1.54)
Diluted (in dollars per share)	$ (0.42)	$ (0.44)	$ (2.12)	$ (1.54)