Note 7 - Share-based Compensation - Compensation Cost (Details) - Selling, General and Administrative Expenses [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share-based compensation	$ 781	$ 620	$ 1,473	$ 1,121
Common Stock [Member]
Share-based compensation	100	100	200	200
Employee and Nonemployee Stock Option [Member]
Share-based compensation	60	53	113	105
Restricted Stock Units (RSUs) [Member]
Share-based compensation	$ 621	$ 467	$ 1,160	$ 816