Note 15 - Stock Based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Stock compensation expense	$ 1,666	$ 1,794	$ 5,243	$ 3,648
General and Administrative Expense [Member]
Stock compensation expense	1,042	1,232	3,366	2,534
Research and Development Expense [Member]
Stock compensation expense	$ 624	$ 562	$ 1,877	$ 1,114