Investments - Schedule of Selected Information about Sales of Fixed Maturities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales			$ 145,824	$ 219,027
Fixed maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	$ 130,119	$ 143,911	145,824	219,027
Gross realized gains	47	0	47	773
Gross realized losses	$ (10,503)	$ (41,168)	$ (10,861)	$ (44,847)