Note 13 - Income Taxes - Aggregate Changes in the Balance of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Balance, beginning of year	$ 1,235	$ 1,046
Additions based on tax positions related to the current year	158	189
Reductions for tax positions related to prior years	(25)	0
Balance, end of year	$ 1,368	$ 1,235