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Investment Securities - Gross unrealized losses (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
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Investment securities available-for-sale |  |
Unrealized losses less than 12 months | $ (19,761) | $ (10,290)
Fair value less than 12 months | 178,719 | 578,270
Unrealized losses over 12 months | (112,503) | (1,681)
Fair value over 12 months | 535,024 | 55,084
Total Unrealized losses | (132,264) | (11,971)
Total Fair value | 713,743 | 633,354
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (3,336) | (3,494)
Fair value less than 12 months | 18,788 | 257,583
Unrealized losses over 12 months | (47,654) |
Fair value over 12 months | 249,623 |
Total Unrealized losses | (50,990) | (3,494)
Total Fair value | 268,411 | 257,583
Unrealized losses less than 12 months | (23,097) | (13,784)
Fair value less than 12 months | 197,507 | 835,853
Unrealized losses over 12 months | (160,157) | (1,681)
Fair value over 12 months | 784,647 | 55,084
Total Unrealized losses | (183,254) | (15,465)
Total Fair value | 982,154 | 890,937
U.S. treasury and government agencies |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (17) |
Fair value less than 12 months | 509 |
Total Unrealized losses | (17) |
Total Fair value | 509 |
Mortgage backed securities - Residential agency |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (10,457) | (10,156)
Fair value less than 12 months | 79,693 | 554,811
Unrealized losses over 12 months | (107,711) | (1,681)
Fair value over 12 months | 507,418 | 55,082
Total Unrealized losses | (118,168) | (11,837)
Total Fair value | 587,111 | 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 | (33,254) |
Fair value over 12 months | 150,861 |
Total Unrealized losses | (33,254) | (3,145)
Total Fair value | 150,861 | 204,373
Mortgage backed securities - Commercial |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (4,835) | (123)
Fair value less than 12 months | 50,437 | 17,470
Unrealized losses over 12 months | (2,276) |
Fair value over 12 months | 13,120 |
Total Unrealized losses | (7,111) | (123)
Total Fair value | 63,557 | 17,470
Asset backed securities |  |
Investment securities available-for-sale |  |
Fair value less than 12 months | 32 |
Fair value over 12 months | 2 | 2
Total Fair value | 34 | 2
Corporate bonds |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months | (4,452) | (11)
Fair value less than 12 months | 48,048 | 5,989
Unrealized losses over 12 months | (2,516) |
Fair value over 12 months | 14,484 |
Total Unrealized losses | (6,968) | (11)
Total Fair value | 62,532 | 5,989
Obligations of state and political agencies. |  |
Investment securities available-for-sale |  |
Unrealized losses less than 12 months |  | (349)
Fair value less than 12 months |  | 53,210
Total Unrealized losses |  | (349)
Total Fair value |  | $ 53,210
Held-to-maturity investment securities |  |
Unrealized losses less than 12 months | (3,336) |
Fair value less than 12 months | 18,788 |
Unrealized losses over 12 months | (14,400) |
Fair value over 12 months | 98,762 |
Total Unrealized losses | (17,736) |
Total Fair value | $ 117,550 |

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