Note 9 - Allowance for Loan Losses and Credit Quality Information - Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Troubled debt restructurings	$ 1,521	$ 2,465
Performing Financial Instruments [Member]
Troubled debt restructurings	457	1,770
Nonperforming Financial Instruments [Member]
Troubled debt restructurings	1,064	695
Residential Portfolio Segment [Member]
Troubled debt restructurings	617	623
Residential Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	356	357
Residential Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	261	266
Commercial Real Estate Portfolio Segment [Member]
Troubled debt restructurings	214	983
Commercial Real Estate Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	0	983
Commercial Real Estate Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	214	0
Consumer Portfolio Segment [Member]
Troubled debt restructurings	655	745
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	66	316
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	589	429
Commercial Portfolio Segment [Member]
Troubled debt restructurings	35	114
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	35	114
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0