Fair Values of Financial Instruments - Summary of Carrying or Reported Values and Corresponding Fair Values for Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	$ 473,092	$ 468,144
Fixed maturity securities--available-for-sale	317,064	321,121
Equity securities	57,147	62,058
Short-term investments		14,120
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	483,575	491,688
Fixed maturity securities--available-for-sale	317,064	321,121
Equity securities	57,147	62,058
Short-term investments		14,120
Cash and cash equivalents	38,682	61,469
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	473,092	468,144
Fixed maturity securities--available-for-sale	317,064	321,121
Equity securities	57,147	62,058
Short-term investments		14,120
Cash and cash equivalents	$ 38,682	$ 61,469