Losses and Loss Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reserves For Losses And Loss Adjustment Expenses [Line Items]
Claims and claim adjustment expenses prior period development	$ 0	$ 8,382	$ 0	$ 11,010
Total incurred, net of reinsurance	61,890	$ 86,830	122,455	$ 159,534
United [Member]
Reserves For Losses And Loss Adjustment Expenses [Line Items]
Total incurred, net of reinsurance	13,700		35,335
Accident Year 2022 and Prior [Member]
Reserves For Losses And Loss Adjustment Expenses [Line Items]
Claims and claim adjustment expenses prior period development	$ 922		$ 4,789