Investments - Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-Sale (Detail) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	$ 338,593,000	$ 324,597,000
Available-for-sale, Gross Unrealized Gains	1,002,000	17,829,000
Available-for-sale, Gross Unrealized Losses	(18,474,000)	(657,000)
Available-for-sale fixed maturity, Fair Value	321,121,000	341,769,000
Available-for-sale securities, credit allowance	0	0
Fixed maturity securities, available-for-sale, allowance for credit losses	0	0
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	166,019,000	202,008,000
Available-for-sale, Gross Unrealized Gains	463,000	14,538,000
Available-for-sale, Gross Unrealized Losses	(9,826,000)	(240,000)
Available-for-sale fixed maturity, Fair Value	156,656,000	216,306,000
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	150,915,000	93,947,000
Available-for-sale, Gross Unrealized Gains	530,000	2,751,000
Available-for-sale, Gross Unrealized Losses	(6,657,000)	(272,000)
Available-for-sale fixed maturity, Fair Value	144,788,000	96,426,000
U.S. Agency-Based Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale, Amortized Cost	5,984,000	7,944,000
Available-for-sale, Gross Unrealized Gains		158,000
Available-for-sale, Gross Unrealized Losses	(538,000)	(13,000)
Available-for-sale fixed maturity, Fair Value	5,446,000	8,089,000
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	15,675,000	20,698,000
Available-for-sale, Gross Unrealized Gains	9,000	382,000
Available-for-sale, Gross Unrealized Losses	(1,453,000)	(132,000)
Available-for-sale fixed maturity, Fair Value	$ 14,231,000	$ 20,948,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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