Note 13 - Fair Value of Financial Instruments - Fair Value Measurements, Recurring Basis (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Available For Sale ("AFS")	$ 541,952,626	$ 550,148,284
Taxable Municipal Bonds [Member]
Available For Sale ("AFS")	52,088,780	50,769,739
Collateralized Mortgage-Backed Securities [Member]
Available For Sale ("AFS")	331,157,574	319,281,268
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Student Loan Pools [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | SBA Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Tax Exempt Municipal Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Taxable Municipal Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage-Backed Securities [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Available For Sale ("AFS")	541,952,626	550,148,284
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Student Loan Pools [Member]
Available For Sale ("AFS")	53,884,324	59,156,982
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | SBA Bonds [Member]
Available For Sale ("AFS")	84,160,160	99,629,967
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Tax Exempt Municipal Bonds [Member]
Available For Sale ("AFS")	20,661,788	21,310,328
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Taxable Municipal Bonds [Member]
Available For Sale ("AFS")	52,088,780	50,769,739
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage-Backed Securities [Member]
Available For Sale ("AFS")	331,157,574	319,281,268
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Student Loan Pools [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | SBA Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Tax Exempt Municipal Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Taxable Municipal Bonds [Member]
Available For Sale ("AFS")	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage-Backed Securities [Member]
Available For Sale ("AFS")	$ 0	$ 0