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Note 8 - Fair Value Measurements - Assets and Liabilities at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands | Mar. 31, 2016 | Dec. 31, 2015
--- | --- | ---
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | $ 248,156 | $ 212,464
US Government Agencies Debt Securities [Member] |  |
Securities available for sale | 248,156 | 212,464
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | 14,453 | 16,475
US States and Political Subdivisions Debt Securities [Member] |  |
Securities available for sale | 14,453 | 16,475
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | 1,241 | 1,319
Collateralized Mortgage Backed Securities [Member] |  |
Securities available for sale | 1,241 | 1,319
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | 6,119 | 5,746
Corporate Debt Securities [Member] |  |
Securities available for sale | 6,119 | 5,746
Other Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | 125 | 127
Other Securities [Member] |  |
Securities available for sale | 125 | 127
Fair Value, Inputs, Level 2 [Member] |  |
Securities available for sale | 270,094 | 236,131
Securities available for sale | $ 270,094 | $ 236,131

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References 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 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563 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 + Details
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