OPERATING SEGMENT DATA - (Operating Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING EXPENSES
Salaries, wages, and benefits	$ 334,829	$ 331,137
Rents, purchased transportation, and other costs of services	199,871	184,699
Fuel, supplies, and expenses	72,662	63,135
Depreciation and amortization	25,394	25,151
Other	28,954	26,598
Restructuring costs	1,631
Total consolidated operating expenses	$ 663,341	$ 630,720