Note 3 - Securities - Available-for-sale Securities by Maturity (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
1-5 years, amortized cost	$ 385,947
1-5 years, fair value	391,254
5-10 years, amortized cost	18,704,471
5-10 years, fair value	18,877,281
After 10 years, amortized cost	34,429,565
After 10 years, fair value	34,929,172
Available-for-sale securities, amortized cost	117,152,760	$ 88,102,659
Available-for-sale securities	118,245,314	86,266,197
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Not due on a single maturity date, amortized cost	13,788,728
Not due on a single maturity date, fair value	13,811,371
Available-for-sale securities, amortized cost	13,788,728
Available-for-sale securities	13,811,371
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Not due on a single maturity date, amortized cost	49,844,049
Not due on a single maturity date, fair value	50,236,236
Available-for-sale securities, amortized cost	49,844,049	50,632,011
Available-for-sale securities	$ 50,236,236	$ 49,476,750

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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