Workers' Compensation Claims - Summarizes Aggregate Workers' Compensation Reserve Activity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Workers Compensation Reserve [Abstract]
Workers' compensation claims liabilities, Beginning balance	$ 279,407	$ 357,746
Add: claims expense accrual
Current period	4,284	33,270
Prior periods	(2,919)	(1,180)
Total expense accrual	1,365	32,090
Less: claim payments related to
Current period	225	1,050
Prior periods	18,034	25,767
Total paid	18,259	26,817
Change in claims incurred in excess of retention limits	133	(356)
Workers' compensation claims liabilities, Ending balance	262,646	362,663
Incurred but not reported (IBNR)	$ 138,604	$ 212,297
Ratio of IBNR to workers' compensation claims liabilities	53.00%	59.00%