Investments - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) Security	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) Security	Jun. 30, 2021 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	178		178
Individual fixed maturity held in unrealized loss position longer than 12 months | Security	0		0
Number of fixed maturity securities, allowance for credit loss | Security	353		353
Fixed maturity securities, allowance for credit loss	$ 276		$ 276		$ 290	$ 195
Available-for-sale, Allowance for Credit Losses	0		0			0
Net realized gains on investments	1,079	$ 1,179	1,817	$ 1,498
Net unrealized gains (losses) on equity securities	(9,942)	$ 3,286	(8,902)	$ 8,797
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, allowance for credit loss	$ 228		$ 228		241	143
Number of majority securities | Security	25		25
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, allowance for credit loss	$ 44		$ 44		$ 45	$ 48
Number of majority securities | Security	325		325
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate			20 years