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Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands | Sep. 30, 2022 | Dec. 31, 2021
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | $ 325,891 | $ 341,769
Equity securities, Fair Value | 57,375 | 64,140
Fair Value, Measurements, Recurring [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 325,891 | 341,769
Total | 383,266 | 405,909
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 14,103 | 20,948
Total | 71,478 | 85,088
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 311,788 | 320,821
Total | 311,788 | 320,821
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 166,161 | 216,306
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] |  |
Available-for-sale fixed maturity, Fair Value | 166,161 | 216,306
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 140,048 | 96,426
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] |  |
Available-for-sale fixed maturity, Fair Value | 140,048 | 96,426
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] |  |
Available-for-sale fixed maturity, Fair Value | 5,579 | 8,089
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] |  |
Available-for-sale fixed maturity, Fair Value | 5,579 | 8,089
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Available-for-sale fixed maturity, Fair Value | 14,103 | 20,948
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] |  |
Available-for-sale fixed maturity, Fair Value | 14,103 | 20,948
Fair Value, Measurements, Recurring [Member] | Common Stock [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Equity securities, Fair Value | 57,375 | 64,140
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, Fair Value | $ 57,375 | $ 64,140

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