Note 9 - Allowance for Loan Losses and Credit Quality Information - Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Troubled debt restructurings	$ 2,708	$ 2,465
Performing Financial Instruments [Member]
Troubled debt restructurings	1,725	1,770
Nonperforming Financial Instruments [Member]
Troubled debt restructurings	983	695
Residential Portfolio Segment [Member]
Troubled debt restructurings	628	623
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	357	357
Residential Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	271	266
Commercial Real Estate Portfolio Segment [Member]
Troubled debt restructurings	1,258	983
Commercial Real Estate Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	966	983
Commercial Real Estate Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	292	0
Consumer Portfolio Segment [Member]
Troubled debt restructurings	731	745
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	311	316
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	420	429
Commercial Portfolio Segment [Member]
Troubled debt restructurings	91	114
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	91	114
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0