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Investment Securities - Schedule of Amortized Cost and Fair Value by Contractual Maturity of Investment Securities HTM and AFS (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Investment securities HTM, Fair value |  |
Amortized Cost | $ 2,727,898 |
Investment securities AFS, Amortized cost |  |
Amortized Cost | 7,826,870 | $ 11,091,254
Investment securities AFS, Fair value |  |
Fair Value | 7,554,168 | 9,788,662
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Investment securities HTM, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,622,457 |
Amortized cost | 2,622,457 |
Investment securities HTM, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,727,898 |
Amortized Cost | 2,727,898 |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,242,750 |
Amortized Cost | 2,242,750 | 7,523,399
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,069,369 |
Fair Value | 2,069,369 | 6,430,379
U.S. Treasury securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 22,741 |
1 to 5 Years | 774,204 |
5 to 10 Years | 385,787 |
More Than 10 Years | 0 |
Amortized Cost | 1,182,732 | 588,082
Investment securities AFS, Fair value |  |
Within One Year | 22,741 |
1 to 5 Years | 792,477 |
5 to 10 Years | 399,145 |
More Than 10 Years | 0 |
Fair Value | 1,214,363 | 597,629
U.S. Government agency securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 29,993 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Amortized Cost | 29,993 | 29,993
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 29,613 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Fair Value | 29,613 | 28,940
Mortgage-backed securities issued by U.S. Government agencies |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 50 |
5 to 10 Years | 3 |
More Than 10 Years | 1,594,596 |
Amortized Cost | 1,594,649 | 1,021,612
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 49 |
5 to 10 Years | 3 |
More Than 10 Years | 1,525,039 |
Fair Value | 1,525,091 | 925,664
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 27 |
5 to 10 Years | 8,890 |
More Than 10 Years | 665,416 |
Amortized Cost | 674,333 | 692,487
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 27 |
5 to 10 Years | 8,762 |
More Than 10 Years | 576,599 |
Fair Value | 585,388 | 587,595
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 1,065,288 |
5 to 10 Years | 1,010,913 |
More Than 10 Years | 17,127 |
Amortized Cost | 2,093,328 | 1,226,672
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 1,080,132 |
5 to 10 Years | 1,026,335 |
More Than 10 Years | 15,146 |
Fair Value | 2,121,613 | 1,209,783
Corporate debt securities and other debt securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 9,085 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Amortized Cost | 9,085 | 9,009
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 8,731 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Fair Value | $ 8,731 | $ 8,672

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