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Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) | Mar. 31, 2018 | Dec. 31, 2017
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Securities available for sale, continuous unrealized loss position, less than 12 months | $ 105,956,000 | $ 60,173,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 2,627,000 | 733,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 190,163,000 | 192,348,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 11,412,000 | 6,826,000
Securities available for sale, continuous unrealized loss position | 296,119,000 | 252,521,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 14,039,000 | 7,559,000
US Government Agencies Debt Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 44,594,000 | 35,677,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 1,464,000 | 434,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 126,600,000 | 115,374,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 9,793,000 | 5,918,000
Securities available for sale, continuous unrealized loss position | 171,194,000 | 151,051,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 11,257,000 | 6,352,000
Collateralized Mortgage Backed Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 14,519,000 | 10,179,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 479,000 | 156,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 18,867,000 | 21,084,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 552,000 | 354,000
Securities available for sale, continuous unrealized loss position | 33,386,000 | 31,263,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 1,031,000 | 510,000
Municipal General Obligation Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 43,826,000 | 12,807,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 615,000 | 114,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 43,537,000 | 54,703,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 1,010,000 | 524,000
Securities available for sale, continuous unrealized loss position | 87,363,000 | 67,510,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 1,625,000 | 638,000
Municipal Revenue Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 1,499,000 | 0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 16,000 | 0
Securities available for sale, continuous unrealized loss position, 12 months or more | 1,159,000 | 1,187,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 57,000 | 30,000
Securities available for sale, continuous unrealized loss position | 2,658,000 | 1,187,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 73,000 | 30,000
Other Debt and Equity Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 1,518,000 | 1,510,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 53,000 | 29,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 0 | 0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 0 | 0
Securities available for sale, continuous unrealized loss position | 1,518,000 | 1,510,000
Securities available for sale, continuous unrealized loss position, unrealized loss | $ 53,000 | $ 29,000

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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