Note 12 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Allowance for loan losses	$ 637,848	$ 626,841
Other real estate owned allowance for loss	286,182	228,354
Write-down of equity securities	2,864	12,631
Capital loss carryover	5,300
Nonaccrual interest		31,692
Post-retirement benefits	544,442	502,661
Unrealized loss on securities available for sale		215,751
Lease liability, net of right of use asset	45,975
Deferred Tax Assets, Net of Valuation Allowance, Total	1,522,611	1,617,930
Deferred tax liabilities
Prepaid captive insurance premium	295,039	273,665
Unrealized gain on securities available for sale	16,182
Depreciation	175,312	164,811
Deferred Tax Liabilities, Total	486,533	438,476
Net deferred tax asset	$ 1,036,078	$ 1,179,454