Note 10 - Stock-based Compensation - Non-cash Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based compensation	$ 2,245	$ 1,786
Share-Based Payment Arrangement, Option [Member]
Share-based compensation	978	1,119
Restricted Stock Units (RSUs) [Member]
Share-based compensation	883	629
Performance Restricted Stock Unit [Member]
Share-based compensation	$ 384	$ 38