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	Jun. 30, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	$ 355,670	$ 338,593
Available-for-sale, Gross Unrealized Gains	1,088	1,002
Available-for-sale, Gross Unrealized Losses	(16,374)	(18,474)
Fixed maturity securities-available-for-sale	340,384	321,121
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	155,935	166,019
Available-for-sale, Gross Unrealized Gains	321	463
Available-for-sale, Gross Unrealized Losses	(8,340)	(9,826)
Fixed maturity securities-available-for-sale	147,916	156,656
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	178,426	150,915
Available-for-sale, Gross Unrealized Gains	767	530
Available-for-sale, Gross Unrealized Losses	(6,066)	(6,657)
Fixed maturity securities-available-for-sale	173,127	144,788
U.S. Agency-Based Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	5,598	5,984
Available-for-sale, Gross Unrealized Losses	(536)	(538)
Fixed maturity securities-available-for-sale	5,062	5,446
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	15,711	15,675
Available-for-sale, Gross Unrealized Gains		9
Available-for-sale, Gross Unrealized Losses	(1,432)	(1,453)
Fixed maturity securities-available-for-sale	$ 14,279	$ 14,231