Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023 USD ($) Security	Dec. 31, 2022 USD ($)
Marketable Securities [Line Items]
Short-term investments	$ 0
Individual fixed maturity held in unrealized loss position | Security	156
Individual fixed maturity held in unrealized loss position longer than 12 months | Security	134
Number of fixed maturity securities, allowance for credit loss | Security	471
Fixed maturity securities, available-for-sale, allowance for credit losses	$ 0	$ 0
Fixed maturity securities, held-to-maturity, allowance for credit losses	182,000	239,000
Held-to-Maturity Securities [Member]
Marketable Securities [Line Items]
Investments on deposit with regulatory agencies	24,400,000
Corporate Bonds [Member]
Marketable Securities [Line Items]
Short-term investments		9,900,000
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 142,000	196,000
Number of majority securities | Security	451
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Short-term investments		1,200,000
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 38,000	40,000
Number of majority securities | Security	17
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Marketable Securities [Line Items]
Short-term investments		$ 3,000,000
Corporate Fixed Income Securities [Member] | Maximum [Member]
Marketable Securities [Line Items]
Investments maturity period using default rate	20 years