Workers Compensation Expense - Worker's compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accrued Workers' Compensation [Line Items]
Service cost	$ 3,974	$ 5,991	$ 7,796
Interest cost	$ 6,041	$ 4,610	$ 4,439
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)	Nonoperating Income (Expense)	Nonoperating Income (Expense)
Net amortization	$ (965)	$ 628	$ 2,363
Total workers' compensation expense
Accrued Workers' Compensation [Line Items]
Total workers' compensation expense	9,327	7,446	18,523
Occupational disease
Accrued Workers' Compensation [Line Items]
Service cost	3,974	5,991
Interest cost	6,041	4,610
Net benefit credit	9,050	11,229	14,598
Traumatic injury claims and assessments
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ 277	$ (3,783)	$ 3,925