Note 6 - Allowance for Loan Losses and Credit Quality Information - Financial Effects of Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Number of Contracts	14	16
Pre- modification Outstanding Recorded Investment	$ 586	$ 2,232
Post- modification Outstanding Recorded Investment	$ 591	$ 2,235
Residential Portfolio Segment [Member]
Number of Contracts	4	2
Pre- modification Outstanding Recorded Investment	$ 215	$ 217
Post- modification Outstanding Recorded Investment	$ 220	$ 220
Commercial Real Estate Portfolio Segment [Member] \| Real Estate Loan [Member]
Number of Contracts	0	1
Pre- modification Outstanding Recorded Investment	$ 0	$ 54
Post- modification Outstanding Recorded Investment	$ 0	$ 54
Commercial Real Estate Portfolio Segment [Member] \| Commercial Real Estate Other [Member]
Number of Contracts	0	2
Pre- modification Outstanding Recorded Investment	$ 0	$ 1,518
Post- modification Outstanding Recorded Investment	$ 0	$ 1,518
Consumer Portfolio Segment [Member]
Number of Contracts	10	10
Pre- modification Outstanding Recorded Investment	$ 371	$ 373
Post- modification Outstanding Recorded Investment	$ 371	$ 373
Commercial Portfolio Segment [Member]
Number of Contracts	0	1
Pre- modification Outstanding Recorded Investment	$ 0	$ 70
Post- modification Outstanding Recorded Investment	$ 0	$ 70

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=118936363&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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