Note 2 - Summary of Significant Accounting Policies - Summary of Stock Compensation Expense by Income Statement Account (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock compensation expense	$ 743	$ 563	$ 759
Cost of Sales [Member]
Stock compensation expense	63	50	59
General and Administrative Expense [Member]
Stock compensation expense	503	380	579
Selling and Marketing Expense [Member]
Stock compensation expense	114	74	54
Research and Development Expense [Member]
Stock compensation expense	$ 63	$ 59	$ 67