Note 9 - Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized tax benefits at the beginning of year	$ 848	$ 711	$ 525
Additions for tax positions of current year	0	74	73
Additions for tax positions of prior years	37	63	113
Reductions for settlements with taxing authorities.	(65)	0	0
Reductions for lapses of the applicable statutes of limitations	0	0	0
Unrecognized tax benefits at the end of the year	$ 820	$ 848	$ 711