Investment Securities - Contractual Maturities of Investments Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
Due in one year	$ 34,034
Due after one year through five years	231,104
Due after five years through ten years	48,465
Due after ten years	188,952
Residential mortgage-backed securities	2,166,142
Amortized Cost	2,668,697	$ 2,173,011
Fair Value
Due in one year	34,197
Due after one year through five years	238,092
Due after five years through ten years	49,318
Due after ten years	186,697
Residential mortgage-backed securities	2,152,301
Total	$ 2,660,605	$ 2,227,612