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Investment Securities - Gross unrealized losses (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
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Investment securities available-for-sale |  |
Unrealized losses less than 12 months | $ (37) | $ (313)
Fair value less than 12 months | 18,437 | 46,067
Unrealized losses over 12 months | (130) | (162)
Fair value over 12 months | 8,623 | 36,019
Total Unrealized losses | (167) | (475)
Total Fair value | 27,060 | 82,086
U. S. Treasury and agencies |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (4) | (5)
Fair value less than 12 months | 1,342 | 1,740
Unrealized losses over 12 months |  | (10)
Fair value over 12 months |  | 9,990
Total Unrealized losses | (4) | (15)
Total Fair value | 1,342 | 11,730
Obligations of state and political agencies |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (27) | (140)
Fair value less than 12 months | 12,420 | 11,959
Unrealized losses over 12 months |  | (21)
Fair value over 12 months |  | 5,798
Total Unrealized losses | (27) | (161)
Total Fair value | 12,420 | 17,757
Mortgage backed securities - Residential Agency |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (5) | (52)
Fair value less than 12 months | 2,664 | 17,131
Unrealized losses over 12 months | (13) | (79)
Fair value over 12 months | 1,691 | 14,036
Total Unrealized losses | (18) | (131)
Total Fair value | 4,355 | 31,167
Mortgage backed securities - Commercial |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months |  | (116)
Fair value less than 12 months |  | 15,235
Unrealized losses over 12 months | (117) | (52)
Fair value over 12 months | 6,932 | 6,195
Total Unrealized losses | (117) | (168)
Total Fair value | 6,932 | 21,430
Asset backed securities |  |
Investment securities available-for-sale |  |
Fair value less than 12 months | 2 | 2
Total Fair value | 2 | $ 2
Corporate bonds |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (1) |
Fair value less than 12 months | 2,009 |
Total Unrealized losses | (1) |
Total Fair value | $ 2,009 |

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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, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 Reference 2: 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=118939692&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=118942371&loc=SL82922954-210456 + Details
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