Investments - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Available for sale, Amortized Cost
Due in one year or less	$ 141,734
Due after one year through five years	327,794
Due after five years through ten years	130,737
Due after ten years	410,586
Agency mortgage-backed securities	758,283
Amortized Cost	1,769,134	$ 1,729,054
Available for sale, Estimated Fair Value
Due in one year or less	140,353
Due after one year through five years	309,375
Due after five years through ten years	117,025
Due after ten years	351,139
Agency mortgage-backed securities	700,381
Securities available-for-sale	1,618,273	1,535,807
Held to maturity, Amortized Cost
Due in one year or less	1,230
Due after one year through five years	81,887
Due after five years through ten years	190,949
Due after ten years	425,053
Agency mortgage-backed securities	52,100
Amortized Cost	751,219	710,650
Held to maturity, Estimated Fair Value
Due in one year or less	1,230
Due after one year through five years	77,227
Due after five years through ten years	183,396
Due after ten years	388,118
Agency mortgage-backed securities	46,676
Held to maturity, fair value	$ 696,647	$ 628,517