Summary of Revenue by Segment and Business Line (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 1,162,576	$ 1,054,360	$ 924,513	$ 893,448	$ 978,560	$ 932,814	$ 855,557	$ 805,859	$ 4,034,897	$ 3,572,790	$ 3,525,595
Intermodal [Member]
Segment Reporting Information [Line Items]
Revenue									2,293,030	2,191,067	2,197,268
Truck brokerage [Member]
Segment Reporting Information [Line Items]
Revenue									822,295	698,500	667,992
Logistics [Member]
Segment Reporting Information [Line Items]
Revenue									804,579	683,223	660,335
Dedicated [Member]
Segment Reporting Information [Line Items]
Revenue									114,993
Operating Segments [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Revenue									3,107,394	2,734,541	2,679,318
Operating Segments [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Revenue									1,029,160	948,735	928,661
Operating Segments [Member] | Intermodal [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Revenue									1,852,884	1,785,865	1,792,046
Operating Segments [Member] | Intermodal [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Revenue									496,733	486,758	483,910
Operating Segments [Member] | Truck brokerage [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Revenue									483,955	391,901	355,402
Operating Segments [Member] | Truck brokerage [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Revenue									340,330	308,055	314,498
Operating Segments [Member] | Logistics [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Revenue									655,543	556,775	531,870
Operating Segments [Member] | Logistics [Member] | Mode LLC [Member]
Segment Reporting Information [Line Items]
Revenue									192,097	153,922	130,253
Operating Segments [Member] | Dedicated [Member] | Hub [Member]
Segment Reporting Information [Line Items]
Revenue									115,012
Intersegment Elims [Member]
Segment Reporting Information [Line Items]
Revenue									(101,657)	(110,486)	(82,384)
Intersegment Elims [Member] | Intermodal [Member]
Segment Reporting Information [Line Items]
Revenue									(56,587)	(81,556)	(78,688)
Intersegment Elims [Member] | Truck brokerage [Member]
Segment Reporting Information [Line Items]
Revenue									(1,990)	(1,456)	(1,908)
Intersegment Elims [Member] | Logistics [Member]
Segment Reporting Information [Line Items]
Revenue									(43,061)	$ (27,474)	$ (1,788)
Intersegment Elims [Member] | Dedicated [Member]
Segment Reporting Information [Line Items]
Revenue									$ (19)