Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	$ 287,589	$ 317,064
Equity securities, at fair value (cost $36,019 and $44,046 in 2024 and 2023, respectively)	53,839	57,147
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	287,589	317,064
Total	341,428	374,211
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	13,654	13,671
Total	67,493	70,818
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	273,935	303,393
Total	273,935	303,393
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	117,889	131,895
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	117,889	131,895
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	151,700	166,753
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	151,700	166,753
Fair Value, Measurements, Recurring [Member] | U.S. Agency-Based Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	4,346	4,745
Fair Value, Measurements, Recurring [Member] | U.S. Agency-Based Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	4,346	4,745
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	13,654	13,671
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturity securities - available-for-sale, at fair value (amortized cost $299,652, allowance for credit losses of $0 in 2024 and amortized cost $326,171, allowance for credit losses of $0 in 2023)	13,654	13,671
Fair Value, Measurements, Recurring [Member] | Common Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost $36,019 and $44,046 in 2024 and 2023, respectively)	53,839	57,147
Fair Value, Measurements, Recurring [Member] | Common Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost $36,019 and $44,046 in 2024 and 2023, respectively)	$ 53,839	$ 57,147