Note 4 - Loans and Allowance for Loan Losses (Details Textual)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Allowance for Loan and Lease Losses, Write-offs	$ 1,710,000	$ 1,055,000	$ 537,000
Financing Receivable, COVID-19, Modifications, Number of Contracts	20
Financing Receivable, COVID-19, Modifications, Amount	$ 28,557,924
Financing Receivable, COVID-19, Modifications, Resumed Scheduled Payment, Percentage of Loan	84.00%
Financing Receivable, COVID-19, Modifications, Projected to Return to Contractual Payment Terms, Percentage of Loan	16.00%
Loans and Leases Receivable, Net Amount, Total	$ 742,149,271	720,732,402
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	$ 2,542,000	$ 2,835,000	3,173,000
Weighted Average Interest Rate On Loans Receivable	4.45%	5.65%
Mortgage Receivable [Member]
Servicing Asset at Amortized Cost, Ending Balance	$ 24,868	$ 29,222
Commercial Loans [Member]
Servicing Asset at Amortized Cost, Ending Balance	62,261,930	51,381,794
Substandard [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	2,500,000	3,200,000
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses, Write-offs	709,000	381,000	110,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	132,000	184,000	$ 216,000
Commercial Portfolio Segment [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Net Amount, Total	$ 37,300,000
Troubled Debt Restructurings [Member]
Allowance for Loan and Lease Losses, Write-offs		0
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total		$ 37,379