Investments - Gross Unrealized Gains and Losses and Cost or Amortized Cost, Allowance for Credit Losses and Fair Value of Investments Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	$ 301,691	$ 326,171
Available-for-sale, Gross Unrealized Gains	1,769	2,688
Available-for-sale, Gross Unrealized Losses	(12,787)	(11,795)
Fixed maturity securities-available-for-sale	290,673	317,064
Debt Securities Available For Sale Allowance For Credit Loss	0	0
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	122,545	138,031
Available-for-sale, Gross Unrealized Gains	260	583
Available-for-sale, Gross Unrealized Losses	(7,013)	(6,719)
Fixed maturity securities-available-for-sale	115,792	131,895
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	159,284	168,134
Available-for-sale, Gross Unrealized Gains	1,509	2,105
Available-for-sale, Gross Unrealized Losses	(4,042)	(3,486)
Fixed maturity securities-available-for-sale	156,751	166,753
U.S. Agency-Based Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	5,032	5,190
Available-for-sale, Gross Unrealized Losses	(502)	(445)
Fixed maturity securities-available-for-sale	4,530	4,745
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	14,830	14,816
Available-for-sale, Gross Unrealized Gains		0
Available-for-sale, Gross Unrealized Losses	(1,230)	(1,145)
Fixed maturity securities-available-for-sale	$ 13,600	$ 13,671