Statutory Accounting and Regulatory Requirements - Insurance Subsidiaries (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Insurance [Abstract]
Capital and surplus	$ 252,486	$ 277,789	$ 365,524
Net income	59,810	53,094	82,390
Net realized gains on investments	$ 3,692	$ 1,695	$ 1,075