Debt Securities - Maturity Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Available-for-Sale, Amortized Cost
Due within one year	$ 56,222
Due after one year through five years	787,336
Due after five years through ten years	16,296
Due after ten years	37,376
Total before mortgage-backed securities	897,230
Mortgage-backed securities	3,887,942
Amortized Cost	4,785,172	$ 5,283,253
Available-for-Sale, Fair Value
Due within one year	55,073
Due after one year through five years	758,562
Due after five years through ten years	15,732
Due after ten years	35,220
Total before mortgage-backed securities	864,587
Mortgage-backed securities	3,571,991
Debt securities, available-for-sale	4,436,578	4,785,719
Held-to-Maturity, Amortized Cost
Due within one year	9,139
Due after one year through five years	938,197
Due after five years through ten years	189,027
Due after ten years	1,351,759
Total before mortgage-backed securities	2,488,122
Mortgage-backed securities	860,576
Amortized Cost	3,348,698	3,502,411
Held-to-Maturity, Fair Value
Due within one year	9,133
Due after one year through five years	894,304
Due after five years through ten years	183,962
Due after ten years	1,186,286
Total before mortgage-backed securities	2,273,685
Mortgage-backed securities	806,864
Total	$ 3,080,549	$ 3,180,194