SEGMENT REPORTING - Summary of Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) employee	Mar. 31, 2017 USD ($) employee	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Total revenues	$ 3,925,327	$ 3,415,125
Net revenues	625,925	568,566
Income from operations	191,585	187,958
Depreciation and amortization	24,241	22,431
Total assets	$ 4,307,776	$ 3,775,744	$ 4,235,834
Average headcount (employee) | employee	15,088	14,279
NAST
Segment Reporting Information [Line Items]
Total revenues	$ 2,786,556	$ 2,360,406
Net revenues	414,769	372,440
Income from operations	174,078	155,877
Depreciation and amortization	6,133	5,590
Total assets	$ 2,383,229	$ 2,126,900
Average headcount (employee) | employee	6,855	6,844
Global Forwarding
Segment Reporting Information [Line Items]
Total revenues	$ 563,118	$ 476,931
Net revenues	123,037	106,546
Income from operations	8,221	16,206
Depreciation and amortization	8,909	8,020
Total assets	$ 805,184	$ 699,139
Average headcount (employee) | employee	4,767	3,926
Robinson Fresh
Segment Reporting Information [Line Items]
Total revenues	$ 598,815	$ 583,785
Net revenues	53,870	56,837
Income from operations	9,307	14,652
Depreciation and amortization	1,173	1,146
Total assets	$ 412,415	$ 409,972
Average headcount (employee) | employee	907	961
All Other and Corporate
Segment Reporting Information [Line Items]
Total revenues	$ 164,392	$ 143,518
Net revenues	34,249	32,743
Income from operations	(21)	1,223
Depreciation and amortization	8,026	7,675
Total assets	$ 706,948	$ 539,733
Average headcount (employee) | employee	2,559	2,548
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	$ 3,925,327	$ 3,415,125
Operating Segments | NAST
Segment Reporting Information [Line Items]
Total revenues	2,663,011	2,259,252
Operating Segments | Global Forwarding
Segment Reporting Information [Line Items]
Total revenues	553,754	468,788
Operating Segments | Robinson Fresh
Segment Reporting Information [Line Items]
Total revenues	550,469	550,445
Operating Segments | All Other and Corporate
Segment Reporting Information [Line Items]
Total revenues	158,093	136,640
Intersegment revenues(1)
Segment Reporting Information [Line Items]
Total revenues	(187,554)	(149,515)
Intersegment revenues(1) | NAST
Segment Reporting Information [Line Items]
Total revenues	123,545	101,154
Intersegment revenues(1) | Global Forwarding
Segment Reporting Information [Line Items]
Total revenues	9,364	8,143
Intersegment revenues(1) | Robinson Fresh
Segment Reporting Information [Line Items]
Total revenues	48,346	33,340
Intersegment revenues(1) | All Other and Corporate
Segment Reporting Information [Line Items]
Total revenues	$ 6,299	$ 6,878