Note 4 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Securities available-for-sale, Amortized Costs	$ 308,241	$ 309,842
Securities available-for-sale, Gross Unrealized Gains	920	808
Securities available-for-sale, Gross Unrealized Losses	4,785	6,328
Securities available-for-sale, Fair Values	304,376	304,282
US Government Agencies Debt Securities [Member]
Securities available-for-sale, Amortized Costs	291,278	291,271
Securities available-for-sale, Gross Unrealized Gains	584	492
Securities available-for-sale, Gross Unrealized Losses	4,649	6,165
Securities available-for-sale, Fair Values	287,213	285,598
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, Amortized Costs	9,977	11,482
Securities available-for-sale, Gross Unrealized Gains	185	211
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	10,162	11,693
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, Amortized Costs	782	845
Securities available-for-sale, Gross Unrealized Gains	82	85
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	864	930
Corporate Debt Securities [Member]
Securities available-for-sale, Amortized Costs	6,015	6,015
Securities available-for-sale, Gross Unrealized Gains	69	20
Securities available-for-sale, Gross Unrealized Losses	127	137
Securities available-for-sale, Fair Values	5,957	5,898
Other Securities [Member]
Securities available-for-sale, Amortized Costs	189	189
Securities available-for-sale, Gross Unrealized Gains	0	0
Securities available-for-sale, Gross Unrealized Losses	9	26
Securities available-for-sale, Fair Values	$ 180	$ 163

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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