Investments - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Available for sale, Amortized Cost
Due in one year or less	$ 98,847
Due after one year through five years	331,727
Due after five years through ten years	83,490
Due after ten years	486,336
Agency mortgage-backed securities	692,187
Amortized Cost	1,692,587	$ 1,358,960
Available for sale, Estimated Fair Value
Due in one year or less	98,463
Due after one year through five years	304,813
Due after five years through ten years	74,785
Due after ten years	367,563
Agency mortgage-backed securities	621,288
Securities available-for-sale	1,466,912	1,366,006
Held to maturity, Amortized Cost
Due in one year or less	675
Due after one year through five years	24,003
Due after five years through ten years	176,436
Due after ten years	387,747
Agency mortgage-backed securities	58,221
Amortized Cost	647,082	430,295
Held to maturity, Estimated Fair Value
Due in one year or less	671
Due after one year through five years	22,507
Due after five years through ten years	157,691
Due after ten years	304,975
Agency mortgage-backed securities	51,944
Fair Value	$ 537,788	$ 434,672