Note 3 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Proceeds from sales of investment securities	$ 20,422	$ 18,338	$ 49,761	$ 85,740
Gross realized gains on sales of securities	187	139	355	399
Gross realized losses on sales of securities	(47)	(106)	(131)	(274)
Gain on sales of investment securities, net	140	33	224	125
US Government Agencies Debt Securities [Member]
Gross realized gains on sales of securities	0	6	0	39
Gross realized losses on sales of securities	(14)	0	(14)	(4)
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	43	115	91	294
Gross realized losses on sales of securities	(1)	(12)	(5)	(90)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities	143	16	226	64
Gross realized losses on sales of securities	(32)	(64)	(112)	(149)
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities	1	2	38	2
Gross realized losses on sales of securities	$ 0	$ (30)	$ 0	$ (31)

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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-Paragraph 11
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 11
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