Investments - Amortized Cost and Estimated Fair Value, Net of Credit Loss Allowance, of Available-For-Sale Securities by Contractual Maturity (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Amortized cost
Due in one year or less	$ 81,196
Due after one year through five years	426,547
Due after five years through ten years	175,670
Due after ten years	309,140
Amortized cost	992,553
Estimated fair value
Due in one year or less	80,030
Due after one year through five years	417,509
Due after five years through ten years	173,800
Due after ten years	289,902
Estimated fair value	$ 961,241