Note 4 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Proceeds from sales of investment securities	$ 117,299	$ 30,235
Gross realized gains on sales of securities	673	263
Gross realized losses on sales of securities	(487)	(219)
Gains on sales of investment securities, net	186	44
US Government Agencies Debt Securities [Member]
Gross realized gains on sales of securities	49
Gross realized losses on sales of securities	(16)	(43)
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	482	262
Gross realized losses on sales of securities	(95)	(71)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities	108
Gross realized losses on sales of securities	(321)	(40)
Corporate Debt Securities [Member]
Gross realized gains on sales of securities		1
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities	34
Gross realized losses on sales of securities	(54)	(19)
Asset-backed Securities [Member]
Gross realized losses on sales of securities	$ (1)	$ (46)

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
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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-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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