Note 12 - Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Stock-based compensation expense	$ 534	$ 619	$ 1,139	$ 1,298
Cost of Sales [Member]
Stock-based compensation expense	23	16	48	47
Research and Development Expense [Member]
Stock-based compensation expense	18	11	36	53
General and Administrative Expense [Member]
Stock-based compensation expense	$ 493	$ 592	$ 1,055	$ 1,198