Note 9 - Allowance for Loan Losses and Credit Quality Information - Non-accrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Non-accrual loans	$ 1,479	$ 2,678
Residential Portfolio Segment [Member]
Non-accrual loans	574	730
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Non-accrual loans	188	201
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Non-accrual loans	105	1,110
Consumer Portfolio Segment [Member]
Non-accrual loans	513	489
Commercial Portfolio Segment [Member]
Non-accrual loans	$ 99	$ 148