Note 5 - Financial Instruments With Off-balance-sheet Credit Risk - Contract Amounts (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Financial instruments with off-balance-sheet risk	$ 38,799,908	$ 43,504,826
Commitments to Extend Credit [Member]
Financial instruments with off-balance-sheet risk	22,617,514	25,739,246
Unused lines of Credit [Member]
Financial instruments with off-balance-sheet risk	$ 16,182,394	$ 17,765,580