OPERATING SEGMENT DATA - (Operating Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
OPERATING EXPENSES
Salaries, wages, and benefits	$ 363,902	$ 363,348	$ 1,068,685	$ 1,048,018
Rents, purchased transportation, and other costs of services	249,110	265,042	706,200	742,338
Fuel, supplies, and expenses	81,023	82,188	241,059	245,718
Depreciation and amortization	29,361	28,026	83,332	81,699
Other	32,959	31,449	96,617	91,112
Multiemployer pension fund withdrawal liability charge				37,922
Restructuring costs		50		766
Total consolidated operating expenses	$ 756,355	$ 770,103	$ 2,195,893	$ 2,247,573