Note 4 - Securities - Sales of Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Proceeds from sales of investment securities	$ 30,235	$ 64,349	$ 51,025
Gross realized gains on sales of securities	263	315	352
Gross realized losses on sales of securities	(219)	(178)	(108)
Gains on investment securities, net	44	137	244
US Government Agencies Debt Securities [Member]
Gross realized gains on sales of securities			25
Gross realized losses on sales of securities	(43)		(13)
US States and Political Subdivisions Debt Securities [Member]
Gross realized gains on sales of securities	262	161	188
Gross realized losses on sales of securities	(71)	(102)	(3)
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Gross realized gains on sales of securities		52	17
Gross realized losses on sales of securities	(40)	(56)	(64)
Corporate Debt Securities [Member]
Gross realized gains on sales of securities	1	79	105
Gross realized losses on sales of securities		(3)	(27)
Commercial Mortgage Backed Securities [Member]
Gross realized gains on sales of securities		3	4
Gross realized losses on sales of securities	(19)	(17)	(1)
Asset-backed Securities [Member]
Gross realized gains on sales of securities		20	13
Gross realized losses on sales of securities	$ (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
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&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/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3151-108585

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