ORGANIZATION AND DESCRIPTION OF THE BUSINESS AND FINANCIAL STATEMENT PRESENTATION (Organization) (Details)	6 Months Ended
	Jun. 30, 2018 segment
Organization and description of business
Number of reportable operating segments	3
Asset-Based
Organization and description of business
Percentage of the Company's revenues, before other revenues and intercompany eliminations, represented by the Asset-Based segment	69.00%
Estimated increase in compounded annual contractual wage and benefit contribution rates (as a percent)	2.00%
Asset-Based | Unionized employees concentration risk | Number of employees
Organization and description of business
Percentage of Asset-Based segment employees covered under collective bargaining agreement with the IBT	82.00%