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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net loss	$ (8,203)	$ (18,600)	$ (23,825)	$ (35,397)
Basic (in shares)	26,850,032	20,858,450	26,636,755	20,533,417
Diluted (in shares)	26,850,032	20,858,450	26,636,755	20,533,417
Basic (in dollars per share)	$ (0.31)	$ (0.89)	$ (0.89)	$ (1.72)
Diluted (in dollars per share)	$ (0.31)	$ (0.89)	$ (0.89)	$ (1.72)