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Securities (Details Textual) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Jun. 30, 2019 | Dec. 31, 2018 | Jun. 30, 2018 | Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale, Realized Gain | $ 6 |  |  |  |  |  |  |
Gain on sale of investments | (6) | $ (3) | $ (18) | $ (5) |  |  |  |
Gross unrealized losses | 1,331 |  | 1,331 |  |  | $ 15,214 |  |
Cumulative OTTI charges | 2,974 | $ 2,974 | 2,974 | $ 2,974 | $ 2,974 | 2,974 | $ 2,974 | $ 7,132
Amortized Cost | 918,591 |  | 918,591 |  |  | 793,084 |  |
Securities available-for-sale | $ 939,944 |  | $ 939,944 |  |  | $ 784,916 |  |
Minimum [Member] |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Basis point spread on variable rate | 1.60% |  | 1.60% |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Basis point spread on variable rate | 1.80% |  | 1.80% |  |  |  |  |

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