Note 9 - Allowance for Loan Losses and Credit Quality Information - Financial Effects of Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Number of Contracts	0	1	3	7
Pre- modification Outstanding Recorded Investment	$ 0	$ 58	$ 387	$ 294
Post- modification Outstanding Recorded Investment	$ 0	$ 58	$ 394	$ 299
Residential Portfolio Segment [Member]
Number of Contracts	0	0	1	3
Pre- modification Outstanding Recorded Investment	$ 0	$ 0	$ 94	$ 176
Post- modification Outstanding Recorded Investment	$ 0	$ 0	$ 101	$ 181
Consumer Portfolio Segment [Member]
Number of Contracts		1		4
Pre- modification Outstanding Recorded Investment		$ 58		$ 118
Post- modification Outstanding Recorded Investment		$ 58		$ 118
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Number of Contracts	0		2
Pre- modification Outstanding Recorded Investment	$ 0		$ 293
Post- modification Outstanding Recorded Investment	$ 0		$ 293

Number of financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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