Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale fixed maturity, Fair Value	$ 426,237	$ 441,146
Equity securities, Fair Value	35,822	27,903
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	426,237	441,146
Total	462,059	469,049
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	29,927	40,126
Total	65,749	68,029
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	396,310	401,020
Total	396,310	401,020
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	275,371	237,775
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	275,371	237,775
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	96,629	133,778
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	96,629	133,778
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	24,310	29,467
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	24,310	29,467
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	29,927	40,126
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	29,927	40,126
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	35,822	27,903
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	$ 35,822	$ 27,903

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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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