Note 12 - Stock-based Compensation Plan - Allocation of Share-based Compensation Expense (Details) - Restricted Stock [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-Based Payment Arrangement, Expense	$ 372	$ 269
Cost of Sales [Member]
Share-Based Payment Arrangement, Expense	11	0
Selling and Marketing Expense [Member]
Share-Based Payment Arrangement, Expense	7	3
Research and Development Expense [Member]
Share-Based Payment Arrangement, Expense	19	10
General and Administrative Expense [Member]
Share-Based Payment Arrangement, Expense	$ 335	$ 256