Note 6 - Accrued Interest Receivable - Summary of Accrued Interest Receivable (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Accrued interest receivable	$ 794,449	$ 785,484
US States and Political Subdivisions Debt Securities [Member]
Accrued interest receivable	120,760	183,453
Residential Mortgage Backed Securities [Member]
Accrued interest receivable	40,099	85,481
Loans Receivable [Member]
Accrued interest receivable	$ 633,590	$ 516,550