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Investment Securities - Gross unrealized losses (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
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Investment securities available-for-sale |  |
Unrealized losses less than 12 months | $ (7,416) | $ (532)
Fair value less than 12 months | 340,254 | 89,457
Unrealized losses over 12 months | (74) | (13)
Fair value over 12 months | 9,059 | 3,667
Total Unrealized losses | (7,490) | (545)
Total Fair value | 349,313 | 93,124
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (631) |
Fair value less than 12 months | 102,695 |
Total Unrealized losses | (631) |
Total Fair value | 102,695 |
Unrealized losses less than 12 months | (8,047) |
Fair value less than 12 months | 442,949 |
Unrealized losses over 12 months | (74) |
Fair value over 12 months | 9,059 |
Total Unrealized losses | (8,121) |
Total Fair value | 452,008 |
U. S. Treasury and agencies |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months |  | (10)
Fair value less than 12 months |  | 4,509
Unrealized losses over 12 months |  | (9)
Fair value over 12 months |  | 1,309
Total Unrealized losses |  | (19)
Total Fair value |  | 5,818
Obligations of state and political agencies |  |
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (29) |
Fair value less than 12 months | 22,550 |
Total Unrealized losses | (29) |
Total Fair value | 22,550 |
Mortgage backed securities - Residential agency |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (7,416) | (432)
Fair value less than 12 months | 340,254 | 68,494
Unrealized losses over 12 months | (74) | (4)
Fair value over 12 months | 9,057 | 2,356
Total Unrealized losses | (7,490) | (436)
Total Fair value | 349,311 | 70,850
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (602) |
Fair value less than 12 months | 80,145 |
Unrealized losses over 12 months | (602) |
Total Fair value | 80,145 |
Asset backed securities |  |
Investment securities available-for-sale |  |
Fair value over 12 months | 2 | 2
Total Fair value | $ 2 | 2
Corporate bonds |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months |  | (90)
Fair value less than 12 months |  | 16,454
Total Unrealized losses |  | (90)
Total Fair value |  | $ 16,454

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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 and held-to-maturity), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References No definition available. + 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 and held-to-maturity), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References No definition available. + Details
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