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SECURITIES AVAILABLE FOR SALE, HELD TO MATURITY, AND EQUITY SECURITIES - Schedule of Securities Available for Sale, Held to Maturity, and Equity Securities (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2024 | Dec. 31, 2023 | Jun. 30, 2024 | Sep. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022
Securities available for sale |  |  |  |  |  |
Amortized Cost | $ 781,946 | $ 1,211,212 |  |  |  |
Gross Unrealized Gains | 739 | 598 |  |  |  |
Gross Unrealized Losses | (120,945) | (189,525) |  |  |  |
Fair Value | 661,740 | 1,022,285 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 512,277 | 543,351 |  |  |  |
Gross Unrealized Gains | 421 | 704 |  |  |  |
Gross Unrealized Losses | (61,504) | (67,827) |  |  |  |
Fair Value | 451,194 | 476,228 |  |  |  |
Allowance | 65 | 68 | $ 65 | $ 69 | $ 71 | $ 91
Equity securities, Amortized Cost | 15,035 | 15,035 |  |  |  |
Equity securities, Gross Unrealized Gains | 0 | 0 |  |  |  |
Equity securities, Gross Unrealized Losses | (1,757) | (2,006) |  |  |  |
Equity securities, Fair Value | 13,278 | 13,029 |  |  |  |
Amortized Cost | 1,309,258 | 1,769,598 |  |  |  |
Gross Unrealized Gains | 1,160 | 1,302 |  |  |  |
Gross Unrealized Losses | (184,206) | (259,358) |  |  |  |
Fair Value | 1,126,212 | 1,511,542 |  |  |  |
Allowance | 65 | 68 |  |  |  |
U.S. Treasuries |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 6,896 | 7,980 |  |  |  |
Gross Unrealized Gains | 11 | 1 |  |  |  |
Gross Unrealized Losses | 0 | 0 |  |  |  |
Fair Value | 6,907 | 7,981 |  |  |  |
Allowance |  | 0 |  |  |  |
Municipal bonds and obligations |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 64,050 | 64,788 |  |  |  |
Gross Unrealized Gains | 289 | 494 |  |  |  |
Gross Unrealized Losses | (1,408) | (1,429) |  |  |  |
Fair Value | 62,931 | 63,853 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 236,707 | 251,046 |  |  |  |
Gross Unrealized Gains | 421 | 698 |  |  |  |
Gross Unrealized Losses | (17,087) | (16,987) |  |  |  |
Fair Value | 220,041 | 234,757 |  |  |  |
Allowance | 45 | 48 | 45 | 48 | 49 | 66
Agency collateralized mortgage obligations |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 308,857 | 426,986 |  |  |  |
Gross Unrealized Gains | 340 | 0 |  |  |  |
Gross Unrealized Losses | (56,765) | (79,112) |  |  |  |
Fair Value | 252,432 | 347,874 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 103,272 | 112,929 |  |  |  |
Gross Unrealized Gains | 0 | 0 |  |  |  |
Gross Unrealized Losses | (15,332) | (18,360) |  |  |  |
Fair Value | 87,940 | 94,569 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Agency mortgage-backed securities |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 276,077 | 492,633 |  |  |  |
Gross Unrealized Gains | 9 | 2 |  |  |  |
Gross Unrealized Losses | (43,155) | (75,155) |  |  |  |
Fair Value | 232,931 | 417,480 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 44,465 | 47,379 |  |  |  |
Gross Unrealized Gains | 0 | 0 |  |  |  |
Gross Unrealized Losses | (7,048) | (8,052) |  |  |  |
Fair Value | 37,417 | 39,327 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Agency commercial mortgage-backed securities |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 86,714 | 174,879 |  |  |  |
Gross Unrealized Gains | 0 | 0 |  |  |  |
Gross Unrealized Losses | (16,148) | (29,553) |  |  |  |
Fair Value | 70,566 | 145,326 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 126,312 | 130,169 |  |  |  |
Gross Unrealized Gains | 0 | 0 |  |  |  |
Gross Unrealized Losses | (22,001) | (24,368) |  |  |  |
Fair Value | 104,311 | 105,801 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Corporate bonds |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 38,697 | 43,291 |  |  |  |
Gross Unrealized Gains | 23 | 34 |  |  |  |
Gross Unrealized Losses | (3,403) | (4,210) |  |  |  |
Fair Value | 35,317 | 39,115 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Other bonds and obligations |  |  |  |  |  |
Securities available for sale |  |  |  |  |  |
Amortized Cost | 655 | 655 |  |  |  |
Gross Unrealized Gains | 67 | 67 |  |  |  |
Gross Unrealized Losses | (66) | (66) |  |  |  |
Fair Value | 656 | 656 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 277 | 288 |  |  |  |
Gross Unrealized Gains | 0 | 0 |  |  |  |
Gross Unrealized Losses | 0 | 0 |  |  |  |
Fair Value | 277 | 288 |  |  |  |
Allowance | 0 | 0 |  |  |  |
Tax advantaged economic development bonds |  |  |  |  |  |
Securities held to maturity |  |  |  |  |  |
Amortized Cost | 1,244 | 1,540 |  |  |  |
Gross Unrealized Gains | 0 | 6 |  |  |  |
Gross Unrealized Losses | (36) | (60) |  |  |  |
Fair Value | 1,208 | 1,486 |  |  |  |
Allowance | $ 20 | $ 20 | $ 20 | $ 21 | $ 22 | $ 25

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