Note 10 - Stock-based Compensation - Allocation of Share-based Compensation Expense (Details) - Restricted Stock [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allocation of Share-based Compensation Expense	$ 454	$ 208	$ 723	$ 395
Cost of Sales [Member]
Allocation of Share-based Compensation Expense	7	0	7	0
Selling and Marketing Expense [Member]
Allocation of Share-based Compensation Expense	6	3	9	6
Research and Development Expense [Member]
Allocation of Share-based Compensation Expense	16	11	26	21
General and Administrative Expense [Member]
Allocation of Share-based Compensation Expense	$ 425	$ 194	$ 681	$ 368