Segment Information - Summary of Segment Information Reconciled to Statement of Income (Detail) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Gross premiums earned	$ 765,512	$ 724,716	$ 577,044
Reinsurance [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	21,032	12,998	3,225
HCPCI [Member]
Segment Reporting Information [Line Items]
Gross premiums earned	$ 417,202	$ 426,501	$ 401,137