ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
ACCRUED EXPENSES
Workers' compensation, third-party casualty, and loss and damage claims reserves	$ 107,149	$ 103,015
Accrued vacation pay	47,730	41,474
Accrued compensation, including retirement benefits	49,148	71,447
Taxes other than income	8,722	8,457
Other	16,000	18,718
Total accrued expenses	$ 228,749	$ 243,111