Note 8 - Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Beginning of year	$ 0	$ 0	$ 298
Current year positions	0	0	0
Prior year positions	0	0	(298)
End of year	$ 0	$ 0	$ 0