Investments - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($) Security	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) Security	Jun. 30, 2024 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	185		185
Number of fixed maturity securities, allowance for credit loss | Security	390		390
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 88		$ 88		$ 100	$ 116
Fixed maturity securities, available-for-sale, allowance for credit losses	0		0			0
Net realized gains (losses) on investments	3,116	$ (117)	3,118	$ (339)
Net unrealized gains (losses) on equity securities	1,829	$ (58)	(1,323)	$ 4,718
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 61		$ 61		71	86
Number of majority securities | Security	11		11
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 27		$ 27		$ 29	$ 30
Number of majority securities | Security	378		378
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate			20 years