Investments - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) Security	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) Security	Jun. 30, 2023 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	170		170
Number of fixed maturity securities, allowance for credit loss | Security	450		450
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 149		$ 149		$ 165	$ 182
Available-for-sale, Allowance for Credit Losses	0		0			0
Net realized gains (losses) on investments	(117)	$ 75	(339)	$ 333
Net unrealized gains (losses) on equity securities	(58)	$ 2,048	4,718	$ 3,417
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 111		$ 111		126	142
Number of majority securities | Security	19		19
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 36		$ 36		$ 37	$ 38
Number of majority securities | Security	428		428
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate			20 years