Workers' Compensation Expense (Occupational Disease Costs Activity and Assumptions) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Self Insurance Reserve [Roll Forward]
Service cost	$ 3,974	$ 5,991	$ 7,796
Interest cost	$ 6,041	$ 4,610	4,439
Discount Rate
Self Insurance Reserve [Roll Forward]
Discount rate	0.0501	0.0521
Occupational disease
Self Insurance Reserve [Roll Forward]
Beginning of period	$ 120,008	$ 167,585
Service cost	3,974	5,991
Interest cost	6,041	4,610
Actuarial (gain) loss	10,721	(48,859)
Benefit and administrative payments	(11,526)	(9,319)
End of period	$ 129,218	$ 120,008	$ 167,585