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, 2025	Dec. 31, 2024	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense, Activity in Liability [Abstract]
Balance, beginning of period	$ 651,309	$ 673,994	$ 696,037
Less amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	112,742	119,746	112,555
Net balance, beginning of period	538,567	554,248	583,482
Add incurred related to:
Current accident year	203,802	192,153	189,659
Prior accident years	(33,865)	(34,886)	(41,396)
Total incurred	169,937	157,267	148,263
Less paid related to:
Current accident year	59,135	52,869	47,207
Prior accident years	141,861	120,079	130,290
Total paid	200,996	172,948	177,497
Net balance, end of period	507,508	538,567	554,248
Add amounts recoverable from reinsurers on unpaid loss and loss adjustment expenses	106,075	112,742	119,746
Balance, end of period	$ 613,583	$ 651,309	$ 673,994