Note 4 - Loans and Allowance for Credit Losses (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2014 USD ($)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Ending Balance		$ 280	$ 9,592
Impaired Financing Receivable, Interest Income, Cash Basis Method, Total	0	0
Impaired Financing Receivable, Recorded Investment, Total	$ 2,252,362	$ 1,503,940
Financing Receivable, Modifications, Number of Contracts	0	0
Loans and Leases Receivable, Related Parties, Ending Balance	$ 33,292	$ 22,000
Troubled Debt Restructurings [Member]
Number of Impaired Loans	1	1
Impaired Financing Receivable, Recorded Investment, Total	$ 60,000	$ 70,000
Proceeds from Impaired Loans, Principal Payment	10,000
Twin Oaks [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Business Combination, Acquired Receivables, Gross Contractual Amount	$ 448,000	$ 432,000
Loans Receivable [Member] | Twin Oaks [Member]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition				$ 3,194,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition				1,324,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net				1,870,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Ending Balance				362,000
Certain Loans Acquired in Transfer, Nonaccretable Difference				$ 1,508,000