REVENUE FROM CONTRACTS WITH CUSTOMERS - Total Revenues Disaggregated by Major Service Line and Timing of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 3,856,132	$ 4,291,900	$ 11,516,182	$ 12,493,264
Transportation and logistics services
Disaggregation of Revenue [Line Items]
Total revenues	3,608,346	4,028,392	10,751,890	11,619,171
Transportation and logistics services | Performance obligations completed over time
Disaggregation of Revenue [Line Items]
Total revenues	3,608,346	4,028,392	10,751,890	11,619,171
Sourcing
Disaggregation of Revenue [Line Items]
Total revenues	247,786	263,508	764,292	874,093
Sourcing | Performance obligations completed at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	247,786	263,508	764,292	874,093
NAST | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	2,826,308	3,224,906	8,495,145	9,296,510
NAST | Transportation and logistics services | Performance obligations completed over time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	2,826,308	3,224,906	8,495,145	9,296,510
NAST | Sourcing | Performance obligations completed at a point in time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Global Forwarding | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	597,695	639,268	1,727,745	1,810,619
Global Forwarding | Transportation and logistics services | Performance obligations completed over time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	597,695	639,268	1,727,745	1,810,619
Global Forwarding | Sourcing | Performance obligations completed at a point in time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
All Other and Corporate | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	432,129	427,726	1,293,292	1,386,135
All Other and Corporate | Transportation and logistics services | Performance obligations completed over time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	184,343	164,218	529,000	512,042
All Other and Corporate | Sourcing | Performance obligations completed at a point in time | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	$ 247,786	$ 263,508	$ 764,292	$ 874,093