Investment Securities - Contractual Maturities of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost
Due in one year	$ 21,808
Due after one year through five years	119,771
Due after five years through ten years	166,510
Due after ten years	547,407
Residential mortgage-backed securities	2,856,322
Amortized Cost	3,711,818	$ 3,740,413
Fair Value
Due in one year	21,680
Due after one year through five years	117,124
Due after five years through ten years	156,912
Due after ten years	479,752
Residential mortgage-backed securities	2,441,934
Total	$ 3,217,402	$ 3,302,312