REVENUE FROM CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 3,627,846	$ 3,908,840	$ 7,432,854	$ 7,660,050
Operating Segments | NAST
Disaggregation of Revenue [Line Items]
Total revenues	2,475,292	2,872,053	5,299,037	5,668,837
Operating Segments | Global Forwarding
Disaggregation of Revenue [Line Items]
Total revenues	707,820	592,483	1,238,204	1,130,050
Operating Segments | All Other and Corporate
Disaggregation of Revenue [Line Items]
Total revenues	444,734	444,304	895,613	861,163
Transportation and logistics services
Disaggregation of Revenue [Line Items]
Total revenues	3,348,611	3,638,612	6,890,729	7,143,544
Transportation and logistics services | Performance obligations completed over time
Disaggregation of Revenue [Line Items]
Total revenues	3,348,611	3,638,612	6,890,729	7,143,544
Transportation and logistics services | Operating Segments | NAST | Performance obligations completed over time
Disaggregation of Revenue [Line Items]
Total revenues	2,475,292	2,872,053	5,299,037	5,668,837
Transportation and logistics services | Operating Segments | Global Forwarding | Performance obligations completed over time
Disaggregation of Revenue [Line Items]
Total revenues	707,820	592,483	1,238,204	1,130,050
Transportation and logistics services | Operating Segments | All Other and Corporate | Performance obligations completed over time
Disaggregation of Revenue [Line Items]
Total revenues	165,499	174,076	353,488	344,657
Sourcing
Disaggregation of Revenue [Line Items]
Total revenues	279,235	270,228	542,125	516,506
Sourcing | Performance obligations completed at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	279,235	270,228	542,125	516,506
Sourcing | Operating Segments | NAST | Performance obligations completed at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Sourcing | Operating Segments | Global Forwarding | Performance obligations completed at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Sourcing | Operating Segments | All Other and Corporate | Performance obligations completed at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	$ 279,235	$ 270,228	$ 542,125	$ 516,506