Investments - Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Amortized Cost
Due in one year or less, Amortized Cost	$ 34,116
Due after one year through five years, Amortized Cost	287,121
Due after five years though ten years, Amortized Cost	315,613
Due after ten years through twenty years, Amortized Cost	39,878
Due after twenty years, Amortized Cost	1,408
Asset-backed securities, Amortized Cost	476,367
Totals, Amortized Cost	1,154,503	$ 1,187,857
Estimated Fair Value
Due in one year or less, Fair Value	33,818
Due after one year through five years, Fair Value	266,167
Due after five years through ten years, Fair Value	275,781
Due after ten years through twenty years, Fair Value	35,118
Due after twenty years, Fair Value	1,270
Asset-backed securities, Fair Value	426,948
Totals, Fair Value	$ 1,039,102	$ 1,218,279