Investments - A Summary of the Company's Realized Gains and Losses on Sales, Calls or Redemptions of Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Marketable Securities [Line Items]
Proceeds from sales	$ 12,223	$ 34,260	$ 41,905
Gross realized investment gains	3,122	1,054	6,729
Gross realized investment losses	(3)	(1,446)	(173)
Net realized investment gains (losses)	3,119	(392)	6,556
Other, including gains (losses) on calls and redemptions	(85)	(184)	23
Net realized gains (losses) on investments	3,034	(576)	6,579
Fixed Maturity Securities Available for Sale [Member]
Marketable Securities [Line Items]
Proceeds from sales	3,991	26,327	28,292
Gross realized investment gains		10	181
Gross realized investment losses	(3)	(310)	(173)
Net realized investment gains (losses)	(3)	(300)	8
Other, including gains (losses) on calls and redemptions	(90)	129
Net realized gains (losses) on investments	(93)	(171)	8
Equity Securities [Member]
Marketable Securities [Line Items]
Proceeds from sales	8,232	7,933	12,688
Gross realized investment gains	3,122	1,044	6,548
Gross realized investment losses		(1,136)
Net realized investment gains (losses)	3,122	(92)	6,548
Net realized gains (losses) on investments	3,122	(92)	6,548
Other [Member]
Marketable Securities [Line Items]
Proceeds from sales			925
Other, including gains (losses) on calls and redemptions	5	(313)	23
Net realized gains (losses) on investments	$ 5	$ (313)	$ 23