Note 5 - Allowance for Loan Losses (Details Textual)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loan Balance For Reviewing High Risk Loans Minimum	$ 250,000	$ 250,000
Impaired Financing Receivable, Number of Loans Below Review Threshold	123		125
Impaired Financing Receivable Recorded Investment Below Review Threshold	$ 3,800,000		$ 3,100,000
Loans and Leases Receivable, Gross, Total	935,271,000	782,027,000	766,796,000
Loans and Leases Receivable, Allowance, Ending Balance	6,789,000	$ 7,277,000	7,159,000	$ 7,508,000
Loans Not Classified as Impaired [Member] | Substandard [Member]
Loans and Leases Receivable, Gross, Total	9,260,000		9,550,000
Loans and Leases Receivable, Allowance, Ending Balance	$ 1,660,000		$ 1,300,000