Note 9 - Allowance for Loan Losses and Credit Quality Information - Financial Effects of Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Number of Contracts	3	8
Pre- modification Outstanding Recorded Investment	$ 47	$ 1,570
Post- modification Outstanding Recorded Investment	$ 50	$ 1,574
Residential Portfolio Segment [Member]
Number of Contracts	1	1
Pre- modification Outstanding Recorded Investment	$ 21	$ 55
Post- modification Outstanding Recorded Investment	$ 24	$ 58
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	1
Pre- modification Outstanding Recorded Investment	$ 0	$ 1,274
Post- modification Outstanding Recorded Investment	$ 0	$ 1,274
Consumer Portfolio Segment [Member]
Number of Contracts	2	4
Pre- modification Outstanding Recorded Investment	$ 26	$ 117
Post- modification Outstanding Recorded Investment	$ 26	$ 118
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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