Schedule II. Condensed Financial Information of Registrant - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Fixed maturity securities—held-to-maturity, at amortized cost net of allowance for credit losses of $0 in 2020 and 2019, (fair value $361 and $0, in 2020 and 2019, respectively)	$ 585,130	$ 599,421
Fixed maturity securities—available-for-sale, at fair value (amortized cost $7,210 in 2020 and 2019)	414,279	441,146
Equity securities, at fair value (cost $10,007 in 2020 and 2019)	43,437	27,903
Short-term investments	45,898	56,548
Total investments	1,088,744	1,125,018
Cash and cash equivalents	61,757	43,813
Property and equipment, net	6,182	6,331
Other assets	10,860	17,587
Total assets	1,470,855	1,492,906
Liabilities:
Accounts payable and other liabilities	38,880	40,089
Total liabilities	1,032,039	1,062,691
Shareholders' equity (net of Treasury stock of $22,370 at December 31, 2020 and 2019)	438,816	430,215	$ 409,762	$ 425,423
Total liabilities and shareholders’ equity	1,470,855	1,492,906
Parent Company [Member]
Assets
Fixed maturity securities—held-to-maturity, at amortized cost net of allowance for credit losses of $0 in 2020 and 2019, (fair value $361 and $0, in 2020 and 2019, respectively)	361
Fixed maturity securities—available-for-sale, at fair value (amortized cost $7,210 in 2020 and 2019)	7,259	7,216
Equity securities, at fair value (cost $10,007 in 2020 and 2019)	11,503	11,779
Short-term investments	9,676	17,967
Investment in subsidiaries	384,774	379,001
Total investments	413,573	415,963
Cash and cash equivalents	23,562	10,551
Notes receivable from subsidiaries	2,140	2,781
Property and equipment, net	1,605	1,720
Federal income tax recoverable	2,705	2,798
Other assets	1,420	804
Total assets	445,005	434,617
Liabilities:
Accounts payable and other liabilities	6,095	4,230
Deferred income taxes	94	172
Total liabilities	6,189	4,402
Shareholders' equity (net of Treasury stock of $22,370 at December 31, 2020 and 2019)	438,816	430,215
Total liabilities and shareholders’ equity	$ 445,005	$ 434,617