Investments - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) Security	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Marketable Securities [Line Items]
Individual fixed maturity held in unrealized loss position | Security	170
Number of fixed maturity securities, allowance for credit loss | Security	455
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 220		$ 239
Available-for-sale, Allowance for Credit Losses	0		0
Net realized gains on investments	258	$ 738
Net unrealized gains (losses) on equity securities	1,369	$ 1,040
Corporate Bonds [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 178		196
Number of majority securities | Security	18
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 40		$ 40
Number of majority securities | Security	434
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate	20 years