Losses and Loss Adjustment Expenses - Losses and LAE (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance, beginning of year*	[1]	$ 246,546	$ 172,410		$ 141,065
Incurred, net of reinsurance, related to:
Current year		235,725	330,836		199,888
Prior years		18,854	40,627		27,637
Total incurred, net of reinsurance		254,579	371,463		227,525
Paid, net of reinsurance, related to:
Current year		(107,204)	(169,641)		(95,809)
Prior years		(139,570)	(127,686)		(100,371)
Total paid, net of reinsurance		(246,774)	(297,327)		(196,180)
Net balance, end of year		254,351	246,546	[1]	172,410	[1]
Add: reinsurance recoverable before allowance for credit losses		330,722	617,219		64,755
Gross balance, end of year		$ 585,073	$ 863,765		$ 237,165

[1] Net balance represents beginning-of-year liability for unpaid losses and LAE less beginning-of-year reinsurance recoverable for unpaid losses and LAE.