Deferred Policy Acquisition Costs - Schedule of Major Categories of the Deferred Policy Acquisition Costs (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Charges Insurers [Abstract]
Agents’ commissions	$ 13,244	$ 14,290
Premium taxes	2,806	2,960
Deferred underwriting expenses	1,760	1,798
Total deferred policy acquisition costs	$ 17,810	$ 19,048	$ 19,734	$ 20,251