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, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Number of Contracts	1	0	4	3
Pre- modification Outstanding Recorded Investment	$ 38	$ 0	$ 284	$ 387
Post- modification Outstanding Recorded Investment	$ 40	$ 0	$ 287	$ 394
Residential Portfolio Segment [Member]
Number of Contracts	1	0	1	1
Pre- modification Outstanding Recorded Investment	$ 38	$ 0	$ 38	$ 94
Post- modification Outstanding Recorded Investment	$ 40	$ 0	$ 40	$ 101
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Number of Contracts	0	0	1	2
Pre- modification Outstanding Recorded Investment	$ 0	$ 0	$ 139	$ 293
Post- modification Outstanding Recorded Investment	$ 0	$ 0	$ 139	$ 293
Consumer Portfolio Segment [Member]
Number of Contracts	0		1
Pre- modification Outstanding Recorded Investment	$ 0		$ 93
Post- modification Outstanding Recorded Investment	$ 0		$ 94
Commercial Portfolio Segment [Member]
Number of Contracts	0		1
Pre- modification Outstanding Recorded Investment	$ 0		$ 14
Post- modification Outstanding Recorded Investment	$ 0		$ 14

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=123577603&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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