Investments - Summary of Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]
Within one year, Amortized Cost	$ 33,100	$ 23,944
After one year through five years, Amortized Cost	79,530	97,996
After five years through ten years, Amortized Cost	73,355	71,233
After ten years, Amortized Cost	$ 126,036	$ 121,257
Investment, Type [Extensible Enumeration]	Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]	Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]
Without single maturity date, Amortized Cost	$ 4,265	$ 4,545
Available-for-sale, Amortized Cost	316,286	318,975
Within one year, Fair Value	32,828	23,806
After one year through five years, Fair Value	78,719	95,500
After five years through ten years, Fair Value	72,208	68,494
After ten years, Fair Value	119,072	115,891
Without single maturity date, Fair value	3,888	4,059
Available-for-sale, Fair Value	$ 306,715	$ 307,750