Note 3 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities available-for-sale, Amortized Costs	$ 309,802	$ 240,234
Securities available-for-sale, Gross Unrealized Gains	808	1,202
Securities available-for-sale, Gross Unrealized Losses	6,328	5,305
Securities available-for-sale, Fair Values	304,282	236,131
US Government Agencies Debt Securities [Member]
Securities available-for-sale, Amortized Costs	291,271	216,897
Securities available-for-sale, Gross Unrealized Gains	492	519
Securities available-for-sale, Gross Unrealized Losses	6,165	4,952
Securities available-for-sale, Fair Values	285,598	212,464
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, Amortized Costs	11,482	15,934
Securities available-for-sale, Gross Unrealized Gains	211	541
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	11,693	16,475
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, Amortized Costs	845	1,199
Securities available-for-sale, Gross Unrealized Gains	85	120
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	930	1,319
Corporate Debt Securities [Member]
Securities available-for-sale, Amortized Costs	6,015	6,015
Securities available-for-sale, Gross Unrealized Gains	20	22
Securities available-for-sale, Gross Unrealized Losses	137	291
Securities available-for-sale, Fair Values	5,898	5,746
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	26	62
Securities available-for-sale, Fair Values	$ 163	$ 127

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=65884222&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=66010992&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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