Note 6 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	3.00%	0.50%	0.30%	10.90%
Income Tax Expense (Benefit), Total	$ 25,081	$ 6,929	$ 5,557	$ (232,000)
Unrecognized Tax Benefits, Ending Balance	0		0
Approximation [Member]
Income Tax Expense (Benefit), Total	$ 26,000	$ 7,000	$ 6,000	$ 232,000