Investments Contractual Maturities of Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Amortized Cost
Due in one year or less, Amortized Cost	$ 293,096
Due after one year through five years, Amortized Cost	1,193,332
Due after five years through ten years, Amortized Cost	575,575
Due after ten years, Amortized Cost	219,649
Total fixed maturities, Amortized Cost	3,991,871	$ 3,663,031
Estimated Fair Value
Due in one year or less, Estimated Fair Value	292,850
Due after one year through five years, Estimated Fair Value	1,198,056
Due after five years through ten years, Estimated Fair Value	573,679
Due after ten years, Estimated Fair Value	180,639
Estimated Fair Value	3,918,078	3,537,563
Asset-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	777,402
Total fixed maturities, Amortized Cost	777,402	729,658
Estimated Fair Value
Without single maturity date, Estimated Fair Value	783,907
Estimated Fair Value	783,907	732,742
Residential mortgage-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	607,220
Total fixed maturities, Amortized Cost	607,220	502,121
Estimated Fair Value
Without single maturity date, Estimated Fair Value	563,791
Estimated Fair Value	563,791	448,874
Commercial mortgage-backed securities
Amortized Cost
Without single maturity date, Amortized Cost	325,597
Total fixed maturities, Amortized Cost	325,597	209,521
Estimated Fair Value
Without single maturity date, Estimated Fair Value	325,156
Estimated Fair Value	$ 325,156	$ 205,105

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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+ References

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+ References

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+ References

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