Fair Values of Financial Instruments - Summary of Carrying Amounts and Corresponding Fair Values for Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities, fair value	$ 385,981	$ 399,721
Fixed maturity securities-available-for-sale	314,726	307,750
Equity securities	55,476	58,629
Short-term investments	11,569	9,338
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities, fair value	399,241	413,061
Fixed maturity securities-available-for-sale	314,726	307,750
Equity securities	55,476	58,629
Short-term investments	11,569	9,338
Cash and cash equivalents	44,753	44,045
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities, fair value	385,981	399,721
Fixed maturity securities-available-for-sale	314,726	307,750
Equity securities	55,476	58,629
Short-term investments	11,569	9,338
Cash and cash equivalents	$ 44,753	$ 44,045