Note 7 - Investments, Held to Maturity ("HTM") (Details Textual)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Held to Maturity, Unrealized Loss Position, Number of Positions	60	54
Debt Securities, Held to Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	38	6
Debt Securities, Held-to-Maturity, Allowance for Credit Loss	$ 0	$ 0
Debt Securities, Held-to-Maturity, Nonaccrual	0
Debt Securities, Held-to-Maturity, 90 Days or More Past Due, Still Accruing	0
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss	946,000
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	174,136,215	167,437,616
Debt Securities, Held-to-Maturity, Fair Value	166,638,696	161,463,573
Asset Pledged as Collateral [Member] | Deposit Accounts, FHLB Advances and Other Borrowings [Member]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	96,200,000	25,300,000
Debt Securities, Held-to-Maturity, Fair Value	$ 90,100,000	$ 24,500,000