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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, 2025 | Dec. 31, 2024
--- | --- | ---
Investment securities HTM, Fair value |  |
Fair value | $ 2,466,265 | $ 2,524,525
Investment securities AFS, Amortized cost |  |
Amortized Cost | 7,862,915 | 8,079,918
Investment securities AFS, Fair value |  |
Fair value | 7,575,468 | 7,551,018
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 | 2,450,885 |
Amortized cost | 2,450,885 |
Investment securities HTM, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,466,265 |
Fair value | 2,466,265 | 2,524,525
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,177,658 |
Amortized Cost | 2,177,658 | 2,294,700
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 0 |
5 to 10 Years | 0 |
More Than 10 Years | 2,006,151 |
Fair value | 2,006,151 | 2,034,035
U.S. Treasury securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 211,755 |
1 to 5 Years | 909,695 |
5 to 10 Years | 78,863 |
More Than 10 Years | 0 |
Amortized Cost | 1,200,313 | 1,214,363
Investment securities AFS, Fair value |  |
Within One Year | 212,743 |
1 to 5 Years | 927,008 |
5 to 10 Years | 81,403 |
More Than 10 Years | 0 |
Fair value | 1,221,154 | 1,212,742
U.S. Government agency securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 29,995 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Amortized Cost | 29,995 | 29,993
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 29,857 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Fair value | 29,857 | 29,163
Mortgage-backed securities issued by U.S. Government agencies |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 29 |
5 to 10 Years | 2 |
More Than 10 Years | 1,504,863 |
Amortized Cost | 1,504,894 | 1,583,331
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 28 |
5 to 10 Years | 2 |
More Than 10 Years | 1,429,676 |
Fair value | 1,429,706 | 1,462,790
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 | 7 |
5 to 10 Years | 7,324 |
More Than 10 Years | 596,196 |
Amortized Cost | 603,527 | 657,453
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 7 |
5 to 10 Years | 7,225 |
More Than 10 Years | 511,967 |
Fair value | 519,199 | 550,201
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 54,439 |
1 to 5 Years | 1,495,206 |
5 to 10 Years | 770,975 |
More Than 10 Years | 16,723 |
Amortized Cost | 2,337,343 | 2,290,968
Investment securities AFS, Fair value |  |
Within One Year | 53,261 |
1 to 5 Years | 1,509,841 |
5 to 10 Years | 782,568 |
More Than 10 Years | 14,540 |
Fair value | 2,360,210 | 2,253,116
Corporate debt securities and other debt securities |  |
Investment securities AFS, Amortized cost |  |
Within One Year | 0 |
1 to 5 Years | 9,185 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Amortized Cost | 9,185 | 9,110
Investment securities AFS, Fair value |  |
Within One Year | 0 |
1 to 5 Years | 9,191 |
5 to 10 Years | 0 |
More Than 10 Years | 0 |
Fair value | $ 9,191 | $ 8,971

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