Note 3 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Proceeds from sales of investment securities	$ 29,339	$ 67,402
Gross realized gains on sales of securities	168	261
Gross realized losses on sales of securities	(84)	(169)
Gain on sales of investment securities, net	84	92
US Government Agencies Debt Securities [Member]
Gross realized gains on sales of securities		33
Gross realized losses on sales of securities		(4)
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	48	181
Gross realized losses on sales of securities	(4)	(77)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities	84	47
Gross realized losses on sales of securities	(80)	(86)
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities	36
Gross realized losses on sales of securities		$ (2)

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26853-111562

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3151-108585

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