Note 2 - Summary of Significant Accounting Policies - Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net loss applicable to common stockholders	$ (5,341)	$ (3,496)	$ (16,719)	$ (9,592)
Weighted average common stock outstanding, basic and diluted (in shares)	5,702	4,768	5,298	4,670
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.94)	$ (0.73)	$ (3.16)	$ (2.05)