LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Assets Sec) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Arrangements
Total assets securing notes payable or held under finance leases	$ 264,497	$ 273,615
Less accumulated depreciation and amortization	78,113	79,961
Net assets securing notes payable or held under finance leases	186,384	193,654
Revenue equipment
Financing Arrangements
Total assets securing notes payable or held under finance leases	245,703	264,396
Land and structures (service centers)
Financing Arrangements
Total assets securing notes payable or held under finance leases	1,794	1,794
Software
Financing Arrangements
Total assets securing notes payable or held under finance leases	1,508	1,484
Service, office, and other equipment
Financing Arrangements
Total assets securing notes payable or held under finance leases	$ 15,492	$ 5,941