Workers Compensation Expense - Worker's compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Total workers' compensation expense
Accrued Workers' Compensation [Line Items]
Total workers' compensation expense	$ 5,433	$ 5,004	$ 10,756	$ 8,956
Occupational disease
Accrued Workers' Compensation [Line Items]
Service cost	1,278	994	2,555	1,987
Interest cost	1,566	1,510	3,131	3,020
Amortization of other actuarial (gains)	(3)	(241)	(6)	(482)
Net benefit credit	2,841	2,263	5,680	4,525
Traumatic injury claims and assessments
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ 2,592	$ 2,741	$ 5,076	$ 4,431