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Securities - Schedule of Debt Securities (Details) - USD ($) $ in Thousands | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
AFS debt securities: |  |
Amortized Cost | $ 9,131,953 | $ 6,916,491
Gross Unrealized Gains | 4,993 | 783
Gross Unrealized Losses | (736,478) | (728,937)
Fair Value | 8,400,468 | 6,188,337
HTM debt securities: |  |
Amortized Cost | 2,948,642 | 2,956,040
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (534,164) | (502,069)
Fair Value | 2,414,478 | 2,453,971
Total debt securities |  |
Amortized Cost | 12,080,595 | 9,872,531
Gross Unrealized Gains | 4,993 | 783
Gross Unrealized Losses | (1,270,642) | (1,231,006)
Fair Value | 10,814,946 | 8,642,308
AFS and HTM, accrued interest | 40,000 | 44,000
Government National Mortgage Association (GNMA) |  |
AFS debt securities: |  |
Amortized Cost | 4,500,000 | 1,300,000
Fair Value | 4,400,000 | 1,200,000
HTM debt securities: |  |
Amortized Cost | 91,000 | 92,000
Fair Value | 73,000 | 75,000
U.S. Treasury securities |  |
AFS debt securities: |  |
Amortized Cost | 676,290 | 1,112,587
Gross Unrealized Gains | 0 | 101
Gross Unrealized Losses | (55,196) | (52,313)
Fair Value | 621,094 | 1,060,375
HTM debt securities: |  |
Amortized Cost | 530,921 | 529,548
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (45,521) | (40,997)
Fair Value | 485,400 | 488,551
U.S. government agency and U.S. government-sponsored enterprise debt securities |  |
AFS debt securities: |  |
Amortized Cost | 410,676 | 412,086
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (49,874) | (47,640)
Fair Value | 360,802 | 364,446
HTM debt securities: |  |
Amortized Cost | 1,002,697 | 1,001,836
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (196,898) | (186,904)
Fair Value | 805,799 | 814,932
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 513,159 | 531,377
Gross Unrealized Gains | 129 | 158
Gross Unrealized Losses | (57,669) | (63,276)
Fair Value | 455,619 | 468,259
HTM debt securities: |  |
Amortized Cost | 491,842 | 493,348
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (93,850) | (88,968)
Fair Value | 397,992 | 404,380
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 5,229,549 | 1,956,927
Gross Unrealized Gains | 4,212 | 380
Gross Unrealized Losses | (241,362) | (229,713)
Fair Value | 4,992,399 | 1,727,594
HTM debt securities: |  |
Amortized Cost | 734,577 | 742,436
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (153,299) | (142,119)
Fair Value | 581,278 | 600,317
Municipal securities |  |
AFS debt securities: |  |
Amortized Cost | 296,360 | 297,283
Gross Unrealized Gains | 47 | 75
Gross Unrealized Losses | (37,912) | (36,342)
Fair Value | 258,495 | 261,016
HTM debt securities: |  |
Amortized Cost | 188,605 | 188,872
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (44,596) | (43,081)
Fair Value | 144,009 | 145,791
Non-agency commercial mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 373,834 | 409,578
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (39,838) | (42,062)
Fair Value | 333,996 | 367,516
Non-agency residential mortgage-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 609,705 | 643,335
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (90,048) | (89,664)
Fair Value | 519,657 | 553,671
Corporate debt securities |  |
AFS debt securities: |  |
Amortized Cost | 653,501 | 653,501
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (150,854) | (151,076)
Fair Value | 502,647 | 502,425
Foreign government bonds |  |
AFS debt securities: |  |
Amortized Cost | 238,592 | 239,333
Gross Unrealized Gains | 605 | 69
Gross Unrealized Losses | (12,001) | (11,528)
Fair Value | 227,196 | 227,874
Asset-backed securities |  |
AFS debt securities: |  |
Amortized Cost | 41,287 | 43,234
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (575) | (934)
Fair Value | 40,712 | 42,300
Collateralized loan obligations (“CLOs”) |  |
AFS debt securities: |  |
Amortized Cost | 89,000 | 617,250
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (1,149) | (4,389)
Fair Value | $ 87,851 | $ 612,861

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