Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity, Fair Value	$ 411,904	$ 414,279
Equity securities, Fair Value	50,843	43,437
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	411,904	414,279
Total	462,747	457,716
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	36,006	29,786
Total	86,849	73,223
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	375,898	384,493
Total	375,898	384,493
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	264,497	276,542
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	264,497	276,542
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	96,373	88,899
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	96,373	88,899
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	15,028	19,052
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	15,028	19,052
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	36,006	29,786
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	36,006	29,786
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	50,843	43,437
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	$ 50,843	$ 43,437

Available for sale securities debt securities and equity securities Fv-Ni.

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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-Name Accounting Standards Codification
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