Fair Value Measurements - Summary of Carrying Amounts and Corresponding Fair Values for Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	$ 455,613	$ 468,144
Fixed maturity securities-available-for-sale	340,384	321,121
Equity securities	65,405	62,058
Short-term investments	46,540	14,120
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	476,401	491,688
Fixed maturity securities-available-for-sale	340,384	321,121
Equity securities	65,405	62,058
Short-term investments	46,540	14,120
Cash and cash equivalents	33,922	61,469
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	455,613	468,144
Fixed maturity securities-available-for-sale	340,384	321,121
Equity securities	65,405	62,058
Short-term investments	46,540	14,120
Cash and cash equivalents	$ 33,922	$ 61,469