Note 3 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Proceeds from sales of investment securities	$ 6,257	$ 13,895	$ 56,017	$ 99,635
Gross realized gains on sales of securities	261	47	615	446
Gross realized losses on sales of securities	(3)	(35)	(133)	(309)
Gain on sales of investment securities, net	258	12	482	137
US Government Agencies Debt Securities [Member]
Gross realized gains on sales of securities	0	10	0	48
Gross realized losses on sales of securities	0	(9)	(14)	(13)
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	249	10	339	305
Gross realized losses on sales of securities	(3)	(6)	(7)	(96)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities	0	22	226	86
Gross realized losses on sales of securities	0	(9)	(112)	(157)
Corporate Debt Securities [Member]
Gross realized gains on sales of securities	12	0	12	0
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities	0	5	38	7
Gross realized losses on sales of securities	$ 0	$ (11)	$ 0	$ (43)

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
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-Section 50
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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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