Note 3 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Proceeds from sales of investment securities	$ 27,176	$ 20,422	$ 39,066	$ 49,761
Gross realized gains on sales of securities	315	187	369	355
Gross realized losses on sales of securities	(251)	(47)	(298)	(131)
Gain on sale of investment securities, net	64	140	71	224
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	227	43	227	91
Gross realized losses on sales of securities	0	(1)	0	(5)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities	81	143	135	226
Gross realized losses on sales of securities	(231)	(32)	(278)	(112)
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities	0	1	0	38
Gross realized losses on sales of securities	(20)	0	(20)	0
Asset-backed Securities [Member]
Gross realized gains on sales of securities	7	0	7	0
US Government Agencies Debt Securities [Member]
Gross realized losses on sales of securities	$ 0	$ (14)	$ 0	$ (14)

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=123581744&loc=d3e27357-111563

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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