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INVESTMENT SECURITIES - Unrealized Gain/Loss on Investment (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
AFS |  |
Amortized cost | $ 1,439,449 | $ 1,509,736
Gross unrealized gains | 154 | 135
Gross unrealized losses | (168,949) | (131,097)
Fair value | 1,270,654 | 1,378,774
Residential mortgage-backed securities |  |
AFS |  |
Amortized cost | 198,589 | 207,445
Gross unrealized gains | 48 | 0
Gross unrealized losses | (15,668) | (10,183)
Fair value | 182,969 | 197,262
Commercial mortgage-backed securities |  |
AFS |  |
Amortized cost | 57,481 | 65,411
Gross unrealized gains | 0 | 0
Gross unrealized losses | (9,918) | (9,362)
Fair value | 47,563 | 56,049
Residential collateralized mortgage obligations |  |
AFS |  |
Amortized cost | 526,683 | 592,449
Gross unrealized gains | 0 | 12
Gross unrealized losses | (47,127) | (39,422)
Fair value | 479,556 | 553,039
Commercial collateralized mortgage obligations |  |
AFS |  |
Amortized cost | 65,686 | 77,909
Gross unrealized gains | 0 | 0
Gross unrealized losses | (6,934) | (7,390)
Fair value | 58,752 | 70,519
Municipal bonds |  |
AFS |  |
Amortized cost | 455,467 | 469,346
Gross unrealized gains | 106 | 41
Gross unrealized losses | (77,275) | (57,839)
Fair value | 378,298 | 411,548
HTM |  |
Amortized cost | 2,389 | 2,441
Gross unrealized gains | 0 | 0
Gross unrealized losses | (96) | (56)
Fair value | 2,293 | 2,385
Corporate debt securities |  |
AFS |  |
Amortized cost | 45,664 | 46,672
Gross unrealized gains | 0 | 74
Gross unrealized losses | (6,696) | (3,801)
Fair value | 38,968 | 42,945
U.S. Treasury securities |  |
AFS |  |
Amortized cost | 22,746 | 23,005
Gross unrealized gains | 0 | 0
Gross unrealized losses | (3,301) | (3,071)
Fair value | 19,445 | 19,934
Agency debentures |  |
AFS |  |
Amortized cost | 67,133 | 27,499
Gross unrealized gains | 0 | 8
Gross unrealized losses | (2,030) | (29)
Fair value | $ 65,103 | $ 27,478

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