Investments - Scheduled Contractual Maturities of Fixed-Maturity Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Cost or Amortized Cost	$ 266,170	$ 10,734
Due after one year through five years, Cost or Amortized Cost	223,153	19,222
Due after five years through ten years, Cost or Amortized Cost	4,380	11,503
Due after ten years, Cost or Amortized Cost	494	494
Fixed-maturity securities, Cost or Amortized Cost	494,197	41,953
Due in one year or less, Estimated Fair Value	265,353	10,826
Due after one year through five years, Estimated Fair Value	214,307	19,820
Due after five years through ten years, Estimated Fair Value	3,797	11,403
Due after ten years, Estimated Fair Value	444	534
Estimated Fair Value Total	$ 483,901	$ 42,583