Fair Values of Financial Instruments - Summary of Carrying or Reported Values and Corresponding Fair Values for Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	$ 468,144	$ 575,850
Fixed maturity securities--available-for-sale	321,121	341,769
Equity securities	62,058	64,140
Short-term investments	14,120	57,431
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	491,688	549,231
Fixed maturity securities--available-for-sale	321,121	341,769
Equity securities	62,058	64,140
Short-term investments	14,120	57,431
Cash and cash equivalents	61,469	70,722
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities--held-to-maturity	468,144	575,850
Fixed maturity securities--available-for-sale	321,121	341,769
Equity securities	62,058	64,140
Short-term investments	14,120	57,431
Cash and cash equivalents	$ 61,469	$ 70,722