Schedule II. Condensed Financial Information of Registrant - Condensed Balance Sheets (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Condensed Balance Sheet Statements, Captions [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 195	$ 274
Fixed maturity securities, fair value	575,850	621,654
Fixed maturity securities, amortized cost	324,597	387,665
Equity securities, cost	44,175	35,787
Net of Treasury stock	22,370	22,370
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Fixed maturity securities, held-to-maturity, allowance for credit losses	0	0
Fixed maturity securities, fair value	0	361
Fixed maturity securities, amortized cost	19,650	7,210
Equity securities, cost	10,007	10,007
Net of Treasury stock	$ 22,370	$ 22,370