Investments - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Available for sale, Amortized Cost
Due in one year or less	$ 97,485
Due after one year through five years	370,543
Due after five years through ten years	70,480
Due after ten years	467,531
Agency mortgage-backed securities	710,642
Amortized Cost	1,716,681	$ 1,729,054
Available for sale, Estimated Fair Value
Due in one year or less	97,369
Due after one year through five years	347,074
Due after five years through ten years	64,238
Due after ten years	395,977
Agency mortgage-backed securities	650,451
Securities available-for-sale	1,555,109	1,535,807
Held to maturity, Amortized Cost
Due in one year or less	720
Due after one year through five years	50,396
Due after five years through ten years	187,914
Due after ten years	426,639
Agency mortgage-backed securities	55,897
Amortized Cost	721,566	710,650
Held to maturity, Estimated Fair Value
Due in one year or less	720
Due after one year through five years	47,082
Due after five years through ten years	177,985
Due after ten years	380,435
Agency mortgage-backed securities	50,331
Fair Value	$ 656,553	$ 628,517