Investments Contractual Maturities of Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less, Amortized Cost	$ 119,449
Due after one year through five years, Amortized Cost	788,144
Due after five years through ten years, Amortized Cost	220,688
Due after ten years, Amortized Cost	232,179
Total fixed maturities, Amortized Cost	2,352,901	$ 1,933,632
Estimated Fair Value
Due in one year or less, Estimated Fair Value	117,363
Due after one year through five years, Estimated Fair Value	758,082
Due after five years through ten years, Estimated Fair Value	195,848
Due after ten years, Estimated Fair Value	188,131
Estimated Fair Value	2,183,686	1,760,100
Asset-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	574,255
Total fixed maturities, Amortized Cost	574,255	361,248
Estimated Fair Value
Without single maturity date, Estimated Fair Value	565,912
Estimated Fair Value	565,912	353,006
Residential mortgage-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	350,674
Total fixed maturities, Amortized Cost	350,674	349,066
Estimated Fair Value
Without single maturity date, Estimated Fair Value	297,602
Estimated Fair Value	297,602	293,962
Commercial mortgage-backed securities
Amortized Cost
Without single maturity date, Amortized Cost	67,512
Total fixed maturities, Amortized Cost	67,512	65,353
Estimated Fair Value
Without single maturity date, Estimated Fair Value	60,748
Estimated Fair Value	$ 60,748	$ 58,867