Note 3 - Investment Securities - Income Earned on Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment securities	$ 33,479	$ 30,613	$ 19,357
Held-to-maturity Securities [Member]
Taxable Investment Income	3,778	5,162	5,839
Non-taxable Investment Income	10,641	11,635	10,625
Available-for-sale Securities [Member]
Taxable Investment Income	17,928	12,129	2,785
Non-taxable Investment Income	$ 1,132	$ 1,687	$ 108

Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities exempt from state, federal and other income tax.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.2)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(b))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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