Income Taxes - Schedule of Company's Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred income tax assets:
Discounting of net unpaid loss and loss adjustment expenses	$ 16,164	$ 18,018
Unearned premiums	6,173	6,560
Accrued expenses and other	2,403	2,385
State income tax	2,468	2,135
Accrued policyholder dividends	1,841	1,989
Accrued insurance-related assessments	1,990	1,901
Net unrealized loss on securities	1,182
Total deferred tax assets	32,221	32,988
Deferred income tax liabilities:
Deferred policy acquisition costs	(4,391)	(4,430)
Unrealized gain on securities available-for-sale		(7,791)
Property and equipment and other	(473)	(298)
Salvage and subrogation	(320)	(428)
Loss reserves adjustment	(4,243)	(5,657)
Total deferred income tax liabilities	(9,427)	(18,604)
Net deferred income taxes	$ 22,794	$ 14,384