Note 9 - Allowance for Loan Losses and Credit Quality Information - Non-accrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Non-accrual loans	$ 1,914	$ 2,081
Residential Portfolio Segment [Member]
Non-accrual loans	647	617
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Non-accrual loans	179	184
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Non-accrual loans	557	0
Consumer Portfolio Segment [Member]
Non-accrual loans	491	659
Commercial Portfolio Segment [Member]
Non-accrual loans	$ 40	$ 621