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Note 3 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) | Dec. 31, 2019 | Dec. 31, 2018
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Securities available for sale, continuous unrealized loss position, less than 12 months | $ 32,243,000 | $ 72,791,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 395,000 | 1,582,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 85,330,000 | 205,540,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 859,000 | 9,775,000
Securities available for sale, continuous unrealized loss position | 117,573,000 | 278,331,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 1,254,000 | 11,357,000
US Government Agencies Debt Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 25,650,000 | 31,220,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 349,000 | 1,136,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 73,913,000 | 136,445,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 793,000 | 8,206,000
Securities available for sale, continuous unrealized loss position | 99,563,000 | 167,665,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 1,142,000 | 9,342,000
Collateralized Mortgage Backed Securities [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 2,838,000 | 11,460,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 28,000 | 136,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 10,423,000 | 23,762,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 54,000 | 656,000
Securities available for sale, continuous unrealized loss position | 13,261,000 | 35,222,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 82,000 | 792,000
Municipal General Obligation Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 3,755,000 | 28,923,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 18,000 | 299,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 994,000 | 43,961,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 12,000 | 866,000
Securities available for sale, continuous unrealized loss position | 4,749,000 | 72,884,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 30,000 | 1,165,000
Municipal Revenue Bonds [Member] |  |
Securities available for sale, continuous unrealized loss position, less than 12 months | 0 | 1,188,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss | 0 | 11,000
Securities available for sale, continuous unrealized loss position, 12 months or more | 0 | 1,372,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss | 0 | 47,000
Securities available for sale, continuous unrealized loss position | 0 | 2,560,000
Securities available for sale, continuous unrealized loss position, unrealized loss | 0 | 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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