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Investment Securities - Gross unrealized losses (Details) - USD ($) $ in Thousands | Sep. 30, 2022 | Dec. 31, 2021
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Investment securities available-for-sale |  |
Unrealized losses less than 12 months | $ (72,985) | $ (10,290)
Fair value less than 12 months | 443,178 | 578,270
Unrealized losses over 12 months | (65,080) | (1,681)
Fair value over 12 months | 281,967 | 55,084
Total Unrealized losses | (138,065) | (11,971)
Total Fair value | 725,145 | 633,354
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (16,300) | (3,494)
Fair value less than 12 months | 94,902 | 257,583
Unrealized losses over 12 months | (36,804) |
Fair value over 12 months | 178,404 |
Total Unrealized losses | (53,104) | (3,494)
Total Fair value | 273,306 | 257,583
Unrealized losses less than 12 months | (89,285) | (13,784)
Fair value less than 12 months | 538,080 | 835,853
Unrealized losses over 12 months | (101,884) | (1,681)
Fair value over 12 months | 460,371 | 55,084
Total Unrealized losses | (191,169) | (15,465)
Total Fair value | 998,451 | 890,937
U. S. Treasury and agencies |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (19) |
Fair value less than 12 months | 529 |
Total Unrealized losses | (19) |
Total Fair value | 529 |
Mortgage backed securities - Residential agency |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (60,983) | (10,156)
Fair value less than 12 months | 325,016 | 554,811
Unrealized losses over 12 months | (63,204) | (1,681)
Fair value over 12 months | 271,347 | 55,082
Total Unrealized losses | (124,187) | (11,837)
Total Fair value | 596,363 | 609,893
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months |  | (3,145)
Fair value less than 12 months |  | 204,373
Unrealized losses over 12 months | (34,268) |
Fair value over 12 months | 153,478 |
Total Unrealized losses | (34,268) | (3,145)
Total Fair value | 153,478 | 204,373
Mortgage backed securities - Commercial |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (5,425) | (123)
Fair value less than 12 months | 54,666 | 17,470
Unrealized losses over 12 months | (1,876) |
Fair value over 12 months | 10,618 |
Total Unrealized losses | (7,301) | (123)
Total Fair value | 65,284 | 17,470
Asset backed securities |  |
Investment securities available-for-sale |  |
Fair value less than 12 months | 22 |
Fair value over 12 months | 2 | 2
Total Fair value | 24 | 2
Corporate bonds |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (6,558) | (11)
Fair value less than 12 months | 62,945 | 5,989
Total Unrealized losses | (6,558) | (11)
Total Fair value | 62,945 | 5,989
Obligations of state and political agencies. |  |
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (16,300) | (349)
Fair value less than 12 months | 94,902 | 53,210
Unrealized losses over 12 months | (2,536) |
Fair value over 12 months | 24,926 |
Total Unrealized losses | (18,836) | (349)
Total Fair value | $ 119,828 | $ 53,210

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