Note 9 - Net Loss Per Share of Common Stock - Summary of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Net loss	$ (15,663)	$ (18,477)	$ (13,057)	$ (11,086)	$ (7,105)	$ (8,004)	$ (47,197)	$ (26,195)
Net loss per share - basic and diluted (in dollars per share)	$ (0.51)			$ (0.53)			$ (1.72)	$ (1.33)
Weighted-average shares used to compute basic and diluted net loss per share (in shares)	30,518			20,763			27,419	19,758