Note 3 - Available-for-sale Securities - Scheduled Maturities (Details) - USD ($)	Sep. 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	29,736,583	23,040,618
Due after one to five years, fair value	30,099,735	22,482,300
Due after five to ten years, amortized cost	8,188,302	10,515,614
Due after five to ten years, fair value	8,426,229	10,543,434
Due after ten years, amortized cost	1,965,730
Due after ten years, fair value	2,046,418
Total, amortized cost	39,890,615	33,959,844
Total, fair value	$ 40,572,382	$ 33,428,658