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Investment Securities - Schedule of Gross Unrealized Losses on Investment Securities AFS (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | $ 40,410 | $ 409,725
Less than 12 months, gross unrealized losses | (483) | (2,666)
12 months or longer, fair value | 3,153,697 | 7,513,154
12 months or longer, gross unrealized losses | (381,427) | (1,331,466)
Total, fair value | 3,194,107 | 7,922,879
Total, gross unrealized losses | (381,910) | (1,334,132)
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 |
Less than 12 months, gross unrealized losses | 0 |
12 months or longer, fair value | 0 |
12 months or longer, gross unrealized losses | 0 |
Total, fair value | 0 |
Total, gross unrealized losses | 0 |
U.S. Government agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 0
Less than 12 months, gross unrealized losses | 0 | 0
12 months or longer, fair value | 29,613 | 28,940
12 months or longer, gross unrealized losses | (380) | (1,053)
Total, fair value | 29,613 | 28,940
Total, gross unrealized losses | (380) | (1,053)
Mortgage-backed securities issued by U.S. Government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 40,410 | 159,402
Less than 12 months, gross unrealized losses | (483) | (1,268)
12 months or longer, fair value | 621,818 | 565,358
12 months or longer, gross unrealized losses | (86,195) | (96,717)
Total, fair value | 662,228 | 724,760
Total, gross unrealized losses | (86,678) | (97,985)
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 215,917
Less than 12 months, gross unrealized losses | 0 | (1,193)
12 months or longer, fair value | 1,655,295 | 6,045,914
12 months or longer, gross unrealized losses | (178,671) | (1,093,019)
Total, fair value | 1,655,295 | 6,261,831
Total, gross unrealized losses | (178,671) | (1,094,212)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 0
Less than 12 months, gross unrealized losses | 0 | 0
12 months or longer, fair value | 554,911 | 587,595
12 months or longer, gross unrealized losses | (89,295) | (104,892)
Total, fair value | 554,911 | 587,595
Total, gross unrealized losses | (89,295) | (104,892)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 34,406
Less than 12 months, gross unrealized losses | 0 | (205)
12 months or longer, fair value | 283,330 | 276,675
12 months or longer, gross unrealized losses | (26,532) | (35,448)
Total, fair value | 283,330 | 311,081
Total, gross unrealized losses | (26,532) | (35,653)
Corporate debt securities and other debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 0
Less than 12 months, gross unrealized losses | 0 | 0
12 months or longer, fair value | 8,730 | 8,672
12 months or longer, gross unrealized losses | (354) | (337)
Total, fair value | 8,730 | 8,672
Total, gross unrealized losses | $ (354) | $ (337)

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