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	Sep. 30, 2025	Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	$ 319,255	$ 318,975
Available-for-sale, Gross Unrealized Gains	3,359	1,396
Available-for-sale, Gross Unrealized Losses	(8,010)	(12,621)
Fixed maturity securities-available-for-sale	314,604	307,750
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	167,375	156,488
Available-for-sale, Gross Unrealized Gains	592	148
Available-for-sale, Gross Unrealized Losses	(6,344)	(8,430)
Fixed maturity securities-available-for-sale	161,623	148,206
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	132,868	143,070
Available-for-sale, Gross Unrealized Gains	2,767	1,248
Available-for-sale, Gross Unrealized Losses	(813)	(2,783)
Fixed maturity securities-available-for-sale	134,822	141,535
U.S. Agency-Based Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	4,097	4,545
Available-for-sale, Gross Unrealized Losses	(337)	(486)
Fixed maturity securities-available-for-sale	3,760	4,059
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	14,915	14,872
Available-for-sale, Gross Unrealized Losses	(516)	(922)
Fixed maturity securities-available-for-sale	$ 14,399	$ 13,950