Note 10 - Stock-based Compensation - Allocation of Share-based Compensation Expense (Details) - Restricted Stock [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allocation of Share-based Compensation Expense	$ 371	$ 85	$ 1,094	$ 480
Cost of Sales [Member]
Allocation of Share-based Compensation Expense	10	0	17	0
Selling and Marketing Expense [Member]
Allocation of Share-based Compensation Expense	8	3	17	9
Research and Development Expense [Member]
Allocation of Share-based Compensation Expense	17	10	43	31
General and Administrative Expense [Member]
Allocation of Share-based Compensation Expense	$ 336	$ 72	$ 1,017	$ 440