Note 9 - Income Taxes - Reconciliation of Unrecognized Tax Benefit (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Balance at beginning of year	$ 275,000	$ 259,000
Additions based on tax positions of prior years	20,000	16,000
Balance at end of year	$ 295,000	$ 275,000