Note 3 - Securities - Available-for-sale Securities by Maturity (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
1-5 years, amortized cost	$ 1,150,000
1-5 years, fair value	1,149,433
5-10 years, amortized cost	36,190,647
5-10 years, fair value	36,551,663
After 10 years, amortized cost	58,207,158
After 10 years, fair value	61,152,414
Available-for-sale securities, amortized cost	159,249,817	$ 117,152,760
Available-for-sale securities	164,120,869	118,245,314
Commercial Mortgage Backed Securities [Member]
Not due on a single maturity date, amortized cost	5,399,385
Not due on a single maturity date, fair value	5,444,447
Available-for-sale securities, amortized cost	5,399,385
Available-for-sale securities	5,444,447
Residential Mortgage Backed Securities [Member]
Not due on a single maturity date, amortized cost	9,249,375
Not due on a single maturity date, fair value	9,452,097
Available-for-sale securities, amortized cost	9,249,375
Available-for-sale securities	9,452,097
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Not due on a single maturity date, amortized cost	49,053,252
Not due on a single maturity date, fair value	50,370,815
Available-for-sale securities, amortized cost	49,053,252	49,844,049
Available-for-sale securities	$ 50,370,815	$ 50,236,236

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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