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Note 3 - Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Securities available-for-sale, amortized cost | $ 336,075 | $ 309,802
Securities available-for-sale, gross unrealized gains | 954 | 808
Securities available-for-sale, gross unrealized losses | 5,642 | 6,328
Securities available-for-sale, fair value | 331,387 | 304,282
US Government Agencies Debt Securities [Member] |  |
Securities available-for-sale, amortized cost | 312,604 | 291,271
Securities available-for-sale, gross unrealized gains | 609 | 492
Securities available-for-sale, gross unrealized losses | 5,494 | 6,165
Securities available-for-sale, fair value | 307,719 | 285,598
US States and Political Subdivisions Debt Securities [Member] |  |
Securities available-for-sale, amortized cost | 16,853 | 11,482
Securities available-for-sale, gross unrealized gains | 100 | 211
Securities available-for-sale, gross unrealized losses | 119 | 0
Securities available-for-sale, fair value | 16,834 | 11,693
Collateralized Mortgage Backed Securities [Member] |  |
Securities available-for-sale, amortized cost | 602 | 845
Securities available-for-sale, gross unrealized gains | 57 | 85
Securities available-for-sale, gross unrealized losses | 0 | 0
Securities available-for-sale, fair value | 659 | 930
Corporate Debt Securities [Member] |  |
Securities available-for-sale, amortized cost | 6,016 | 6,015
Securities available-for-sale, gross unrealized gains | 188 | 20
Securities available-for-sale, gross unrealized losses | 29 | 137
Securities available-for-sale, fair value | $ 6,175 | 5,898
Other Securities [Member] |  |
Securities available-for-sale, amortized cost |  | 189
Securities available-for-sale, gross unrealized gains |  | 0
Securities available-for-sale, gross unrealized losses |  | 26
Securities available-for-sale, fair value |  | $ 163

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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=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 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&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=82896770&loc=d3e26610-111562 + Details
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- Definition 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 -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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- Definition 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 -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + 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) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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