LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Assets Sec) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing Arrangements
Total assets securing notes payable or held under capital leases	$ 260,732	$ 222,367
Less accumulated depreciation and amortization	83,554	61,643
Net assets securing notes payable or held under capital leases	177,178	160,724
Revenue equipment
Financing Arrangements
Total assets securing notes payable or held under capital leases	258,412	220,566
Land and structures (service centers)
Financing Arrangements
Total assets securing notes payable or held under capital leases	1,794	1,794
Software
Financing Arrangements
Total assets securing notes payable or held under capital leases	486
Service, office, and other equipment
Financing Arrangements
Total assets securing notes payable or held under capital leases	$ 40	$ 7