Investments - Amortized Cost and Fair Value of Investments With Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 101,298
Due after one year through five years	599,340
Due after five years through ten years	296,330
Due after ten years	178,289
Perpetual maturity securities	3,802
Amortized Cost	1,179,059	$ 1,152,852
Fair Value
Due in one year or less	99,287
Due after one year through five years	547,492
Due after five years through ten years	249,578
Due after ten years	152,021
Perpetual maturity securities	3,130
Fair Value	$ 1,051,508	$ 1,014,626