Investments - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) Security	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Security	Sep. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	222		222
Number of fixed maturity securities, allowance for credit loss | Security	484		484
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 255		$ 255		$ 276	$ 195
Available-for-sale, Allowance for Credit Losses	0		0			0
Net realized gains (losses) on investments	585	$ (8)	2,402	$ 1,490
Net unrealized gains (losses) on equity securities	(4,082)	$ (771)	(12,984)	$ 8,026
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 208		$ 208		228	143
Number of majority securities | Security	23		23
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 44		$ 44		$ 44	$ 48
Number of majority securities | Security	458		458
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate			20 years