Note 3 - Available-for-sale Securities - Scheduled Maturities (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Due in one year or less, amortized cost		$ 403,612
Due in one year or less, fair value		402,924
Due after one to five years, amortized cost	23,546,233	23,040,618
Due after one to five years, fair value	23,794,584	22,482,300
Due after five to ten years, amortized cost	7,488,721	10,515,614
Due after five to ten years, fair value	7,563,485	10,543,434
Due after ten years, amortized cost	3,178,345
Due after ten years, fair value	3,312,062
Total, amortized cost	34,213,299	33,959,844
Total, fair value	$ 34,670,131	$ 33,428,658