Liability for Unpaid Losses and Loss Adjustment Expenses - Change in Liability for Unpaid Losses and LAE (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at beginning of year	$ 322,465	$ 267,760	$ 472,829
Less: Reinsurance recoverable	(119,522)	(123,221)	(393,365)
Net balance at beginning of period	202,943	144,539	79,464
Incurred (recovered) related to current year	724,768	700,473	515,338
Incurred (recovered) related to prior years	54,437	58,337	88,068
Total incurred	779,205	758,810	603,406
Paid related to Current year	526,695	513,308	391,161
Paid related to Prior years	225,097	187,098	147,170
Total paid	751,792	700,406	538,331
Net balance at end of period	230,356	202,943	144,539
Plus: Reinsurance recoverable	115,860	119,522	123,221
Balance at end of year	$ 346,216	$ 322,465	$ 267,760