Investment Securities - Contractual Maturities of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Amortized Cost
Due in one year	$ 58,761
Due after one year through five years	30,364
Due after five years through ten years	163,250
Due after ten years	511,700
Residential mortgage-backed securities	2,777,381
Amortized Cost	3,541,456	$ 3,532,220
Fair Value
Due in one year	58,459
Due after one year through five years	30,347
Due after five years through ten years	156,951
Due after ten years	447,538
Residential mortgage-backed securities	2,457,228
Total	$ 3,150,523	$ 3,028,284