SEGMENT REPORTING - Summary of Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($) employee	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($) employee	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Total Revenues	$ 3,784,451	$ 3,355,754	$ 10,909,594	$ 9,729,438
Net Revenues	593,846	558,462	1,736,201	1,716,012
Income from Operations	194,465	211,267	564,243	643,966
Depreciation and amortization	23,963	17,657	69,340	52,716
Total assets	$ 4,175,588	$ 3,664,062	$ 4,175,588	$ 3,664,062	$ 3,687,758
Average headcount (employee) | employee	14,903	13,706	14,590	13,478
NAST
Segment Reporting Information [Line Items]
Total Revenues	$ 2,585,216	$ 2,331,915	$ 7,439,416	$ 6,667,821
Net Revenues	377,403	378,073	1,109,749	1,161,074
Income from Operations	151,392	171,733	447,553	516,805
Depreciation and amortization	5,808	5,547	17,104	16,551
Total assets	$ 2,297,980	$ 2,115,467	$ 2,297,980	$ 2,115,467
Average headcount (employee) | employee	6,998	6,869	6,921	6,767
Global Forwarding
Segment Reporting Information [Line Items]
Total Revenues	$ 560,007	$ 399,572	$ 1,573,198	$ 1,122,300
Net Revenues	129,842	93,368	357,411	283,458
Income from Operations	31,125	17,047	75,006	56,300
Depreciation and amortization	8,455	5,073	24,574	15,231
Total assets	$ 840,762	$ 625,267	$ 840,762	$ 625,267
Average headcount (employee) | employee	4,301	3,559	4,113	3,523
Robinson Fresh
Segment Reporting Information [Line Items]
Total Revenues	$ 656,918	$ 622,640	$ 1,937,375	$ 1,897,882
Net Revenues	54,253	57,036	171,936	183,041
Income from Operations	11,586	17,733	40,487	62,777
Depreciation and amortization	1,190	983	3,534	2,590
Total assets	$ 413,520	$ 405,832	$ 413,520	$ 405,832
Average headcount (employee) | employee	970	956	966	939
All Other and Corporate
Segment Reporting Information [Line Items]
Total Revenues	$ 152,479	$ 122,452	$ 442,311	$ 360,402
Net Revenues	32,348	29,985	97,105	88,439
Income from Operations	362	4,754	1,197	8,084
Depreciation and amortization	8,510	6,054	24,128	18,344
Total assets	$ 623,326	$ 517,496	$ 623,326	$ 517,496
Average headcount (employee) | employee	2,634	2,322	2,590	2,249
Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	$ 3,784,451	$ 3,355,754	$ 10,909,594	$ 9,729,438
Operating Segments | NAST
Segment Reporting Information [Line Items]
Total Revenues	2,469,420	2,252,187	7,110,223	6,456,281
Operating Segments | Global Forwarding
Segment Reporting Information [Line Items]
Total Revenues	552,134	390,830	1,549,742	1,098,715
Operating Segments | Robinson Fresh
Segment Reporting Information [Line Items]
Total Revenues	613,646	590,385	1,821,094	1,814,682
Operating Segments | All Other and Corporate
Segment Reporting Information [Line Items]
Total Revenues	149,251	122,352	428,535	359,760
Intersegment revenues(1)
Segment Reporting Information [Line Items]
Total Revenues	(170,169)	(120,825)	(482,706)	(318,967)
Intersegment revenues(1) | NAST
Segment Reporting Information [Line Items]
Total Revenues	115,796	79,728	329,193	211,540
Intersegment revenues(1) | Global Forwarding
Segment Reporting Information [Line Items]
Total Revenues	7,873	8,742	23,456	23,585
Intersegment revenues(1) | Robinson Fresh
Segment Reporting Information [Line Items]
Total Revenues	43,272	32,255	116,281	83,200
Intersegment revenues(1) | All Other and Corporate
Segment Reporting Information [Line Items]
Total Revenues	$ 3,228	$ 100	$ 13,776	$ 642