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Note 2 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) | Mar. 31, 2019 | Dec. 31, 2018
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Securities available for sale, continuous unrealized loss position, less than 12 months | $ 4,159,000 | $ 72,791,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 3,000 | 1,582,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 220,427,000 | 205,540,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 7,860,000 | 9,775,000
Securities available for sale, continuous unrealized loss position | 224,586,000 | 278,331,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 7,863,000 | 11,357,000
US Government Agencies Debt Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 0 | 31,220,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 0 | 1,136,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 153,927,000 | 136,445,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 6,883,000 | 8,206,000
Securities available for sale, continuous unrealized loss position | 153,927,000 | 167,665,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 6,883,000 | 9,342,000
Collateralized Mortgage Backed Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 3,404,000 | 11,460,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 1,000 | 136,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 26,840,000 | 23,762,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 551,000 | 656,000
Securities available for sale, continuous unrealized loss position | 30,244,000 | 35,222,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 552,000 | 792,000
Municipal General Obligation Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 253,000 | 28,923,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 1,000 | 299,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 38,347,000 | 43,961,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 390,000 | 866,000
Securities available for sale, continuous unrealized loss position | 38,600,000 | 72,884,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 391,000 | 1,165,000
Municipal Revenue Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 502,000 | 1,188,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 1,000 | 11,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 1,313,000 | 1,372,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 36,000 | 47,000
Securities available for sale, continuous unrealized loss position | 1,815,000 | 2,560,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 37,000 | 58,000
Other Debt and Equity Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 0 | 0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 0 | 0
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 | 0 | 0
Securities available for sale, continuous unrealized loss position, unrealized loss | $ 0 | $ 0

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