Investments - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) Security	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Security	Jun. 30, 2022 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	186		186
Number of fixed maturity securities, allowance for credit loss | Security	458		458
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 204		$ 204		$ 220	$ 239
Available-for-sale, Allowance for Credit Losses	0		0			0
Net realized gains on investments	75	$ 1,079	333	$ 1,817
Net unrealized gains (losses) on equity securities	2,048	$ (9,942)	3,417	$ (8,902)
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 161		$ 161		178	196
Number of majority securities | Security	18		18
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 41		$ 41		$ 40	$ 40
Number of majority securities | Security	437		437
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate			20 years