Loss and Loss Adjustment Expenses - Reconciliation of Beginning and Ending Reserve Balances, Net of Related Amounts Recoverable from Reinsurers (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense, Activity in Liability [Abstract]
Balance, beginning of period	$ 696,037	$ 745,278	$ 760,561
Less amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	112,555	119,266	105,707
Net balance, beginning of period	583,482	626,012	654,854
Add incurred related to:
Current accident year	189,659	192,907	222,715
Prior accident years	(41,396)	(40,591)	(61,917)
Total incurred	148,263	152,316	160,798
Less paid related to:
Current accident year	47,207	50,954	52,292
Prior accident years	130,290	143,892	137,348
Total paid	177,497	194,846	189,640
Net balance, end of period	554,248	583,482	626,012
Add amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	119,746	112,555	119,266
Balance, end of period	$ 673,994	$ 696,037	$ 745,278