Investment Securities - Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity, amortized cost, one year or less	$ 1,906
Held-to-maturity, amortized cost, after one through five years	58,191
Held-to-maturity, amortized cost, after five through ten years	393,485
Held-to-maturity, amortized cost, after ten years	2,116,236
Held-to-maturity, amortized cost, securities not due on a single maturity date	1,070,032
Amortized Cost	3,639,850	$ 3,729,502
Held-to-maturity, fair value, one year or less	1,904
Held-to-maturity, fair value, after one through five years	54,579
Held-to-maturity, fair value, after five through ten years	345,000
Held-to-maturity, fair value, after ten years	1,611,970
Held-to-maturity, fair value, securities not due on a single maturity date	936,498
Held-to-maturity, fair value, total	2,949,951	3,135,370
Available-for-sale, amortized cost, one year or less	4,170
Available-for-sale, amortized cost, after one through five years	106,939
Available-for-sale, amortized cost, after five through ten years	194,665
Available-for-sale, amortized cost, after ten years	1,001,235
Available-for-sale, amortized cost, securities not due on a single maturity date	1,545,539
Available-for-sale, amortized cost, other securities (no maturity)	226
Amortized Cost	2,852,774	3,509,709
Available-for-sale, fair value, one year or less	4,148
Available-for-sale, fair value, after one through five years	106,602
Available-for-sale, fair value, after five through ten years	181,393
Available-for-sale, fair value, after ten years	844,298
Available-for-sale, fair value, securities not due on a single maturity date	1,392,759
Available-for-sale, fair value, other securities (no maturity)	226
Available-for-sale, fair value, total	$ 2,529,426	$ 3,152,153