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Securities - Schedule of Debt Securities (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
AFS debt securities: |  |
Amortized Cost | $ 6,976,331 | $ 6,879,225
Gross Unrealized Gains | 138 | 498
Gross Unrealized Losses | (936,632) | (844,730)
Fair Value | 6,039,837 | 6,034,993
HTM debt securities: |  |
Amortized Cost | 2,964,235 | 3,001,868
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (656,187) | (546,697)
Fair Value | 2,308,048 | 2,455,171
Total debt securities |  |
Amortized Cost | 9,940,566 | 9,881,093
Gross Unrealized Gains | 138 | 498
Gross Unrealized Losses | (1,592,819) | (1,391,427)
Fair Value | 8,347,885 | 8,490,164
U.S. Treasury securities |  |
AFS debt securities: |  |
Amortized Cost | 974,615 | 676,306
Gross Unrealized Gains | 48 | 0
Gross Unrealized Losses | (70,562) | (70,103)
Fair Value | 904,101 | 606,203
HTM debt securities: |  |
Amortized Cost | 528,169 | 524,081
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (57,551) | (52,612)
Fair Value | 470,618 | 471,469
U.S. government agency and U.S. government-sponsored enterprise debt securities |  |
AFS debt securities: |  |
Amortized Cost | 512,712 | 517,806
Gross Unrealized Gains | 0 | 67
Gross Unrealized Losses | (65,248) | (56,266)
Fair Value | 447,464 | 461,607
HTM debt securities: |  |
Amortized Cost | 1,001,298 | 998,972
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (249,007) | (209,560)
Fair Value | 752,291 | 789,412
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 545,086 | 577,392
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (82,754) | (77,123)
Fair Value | 462,332 | 500,269
HTM debt securities: |  |
Amortized Cost | 494,787 | 506,965
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (112,623) | (98,566)
Fair Value | 382,164 | 408,399
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 1,983,284 | 2,011,054
Gross Unrealized Gains | 15 | 41
Gross Unrealized Losses | (288,957) | (248,900)
Fair Value | 1,694,342 | 1,762,195
HTM debt securities: |  |
Amortized Cost | 750,888 | 782,141
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (183,488) | (148,230)
Fair Value | 567,400 | 633,911
Municipal securities |  |
AFS debt securities: |  |
Amortized Cost | 301,408 | 303,884
Gross Unrealized Gains | 0 | 3
Gross Unrealized Losses | (57,852) | (46,788)
Fair Value | 243,556 | 257,099
HTM debt securities: |  |
Amortized Cost | 189,093 | 189,709
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (53,518) | (37,729)
Fair Value | 135,575 | 151,980
Non-agency commercial mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 418,451 | 447,512
Gross Unrealized Gains | 0 | 213
Gross Unrealized Losses | (53,131) | (49,396)
Fair Value | 365,320 | 398,329
Non-agency residential mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 687,674 | 762,202
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (116,887) | (112,978)
Fair Value | 570,787 | 649,224
Corporate debt securities |  |
AFS debt securities: |  |
Amortized Cost | 653,501 | 673,502
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (178,067) | (147,228)
Fair Value | 475,434 | 526,274
Foreign government bonds |  |
AFS debt securities: |  |
Amortized Cost | 237,531 | 241,165
Gross Unrealized Gains | 75 | 174
Gross Unrealized Losses | (14,816) | (14,286)
Fair Value | 222,790 | 227,053
Asset-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 44,819 | 51,152
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (1,062) | (2,076)
Fair Value | 43,757 | 49,076
Collateralized loan obligations (“CLOs”) |  |
AFS debt securities: |  |
Amortized Cost | 617,250 | 617,250
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (7,296) | (19,586)
Fair Value | $ 609,954 | $ 597,664

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