Investments - Summary of Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Schedule of Available-for-sale Securities [Line Items]
Net investment income	$ 7,426	$ 2,654	$ 13,416	$ 5,175
Less: Investment expenses	827	491	1,235	1,012
Net investment income, less investment expenses	6,599	2,163	12,181	4,163
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Net investment income	5,015	2,428	8,038	4,703
Equity Securities[Member]
Schedule of Available-for-sale Securities [Line Items]
Net investment income	57	0	90	0
Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Net investment income	2,246	144	4,449	160
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Net investment income	$ 108	$ 82	$ 839	$ 312