Note 4 - Available-for-sale Securities - Scheduled Maturities (Details) - USD ($)	Dec. 31, 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	27,151,751	23,040,618
Due after one to five years, fair value	27,510,536	22,482,300
Due after five to ten years, amortized cost	14,048,273	10,515,614
Due after five to ten years, fair value	14,163,270	10,543,434
Due after ten years, amortized cost	2,904,807
Due after ten years, fair value	2,843,372
Total, amortized cost	44,104,831	33,959,844
Total, fair value	$ 44,517,178	$ 33,428,658