Note 9 - Allowance for Loan Losses and Credit Quality Information - Non-accrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Non-accrual loans	$ 5,485	$ 3,144
Residential Portfolio Segment [Member]
Non-accrual loans	1,073	949
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Non-accrual loans	243	35
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Non-accrual loans	3,446	1,329
Consumer Portfolio Segment [Member]
Non-accrual loans	526	553
Commercial Portfolio Segment [Member]
Non-accrual loans	$ 197	$ 278