Statutory Accounting and Regulatory Requirements - Insurance Subsidiaries (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Insurance [Abstract]
Capital and surplus	$ 254,856	$ 252,486	$ 277,789
Net income	56,637	59,810	53,094
Net realized gains on investments	$ 5,470	$ 3,692	$ 1,695