Note 4 - Loans and Allowance for Loan Losses - Summary of Classes of Loans on Non-accrual Status (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Total nonaccrual loans	$ 1,935	$ 2,334
Commercial Portfolio Segment [Member]
Total nonaccrual loans	890	1,152
Commercial Real Estate Portfolio Segment [Member]
Total nonaccrual loans	418	566
Residential Portfolio Segment [Member]
Total nonaccrual loans	492	469
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Total nonaccrual loans	135	147
Consumer Portfolio Segment [Member] | Other Loan [Member]
Total nonaccrual loans	$ 0	$ 0