Premiums Receivable - Summary of Activity in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Premiums Receivable, Allowance for Doubtful Accounts [Roll Forward]
Balance, beginning of year	$ 4,791	$ 5,112
Provision for credit loss expense	1,090	1,278
Write-offs	(1,495)	(1,599)
Balance, end of year	$ 4,386	$ 4,791