Investment Securities - Debt Maturities (Details) - Investment securities: - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due within one year	$ 589,475
Due after one year through five years	1,171,601
Due after five years through ten years	2,534,914
Due after ten years	818,486
Available-for-sale, Amortized Cost	5,114,476	$ 4,769,426
Fair Value
Due within one year	584,714
Due after one year through five years	1,135,888
Due after five years through ten years	2,358,496
Due after ten years	794,316
Total, Fair Value	$ 4,873,414	$ 4,579,564
Weighted- Average Yield
Due within one year	1.35%
Due after one year through five years	4.06%
Due after five years through ten years	4.39%
Due after ten years	5.61%
Total, Weighted-Average Yield	4.16%