Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Fixed maturity securities, held-to-maturity, allowance for credit losses	$ 172	$ 274
Fixed maturity securities, fair value	569,445	621,654
Fixed maturity securities, available-for-sale, allowance for credit losses	0	0
Fixed maturity securities, amortized cost	322,863	387,665
Equity securities, cost	40,674	35,787
Amounts recoverable from reinsurers, allowance for credit losses	389	452
Premiums receivable, allowance for credit losses	$ 4,414	$ 4,791
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	20,622,304	20,589,309
Common stock, shares outstanding	19,364,054	19,331,059
Treasury stock, shares	1,258,250	1,258,250