Revenue from Contracts with Customers - Summary of Disaggregated Revenue by Business Line (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 981,320	$ 779,243	$ 1,900,873	$ 1,618,102
Intermodal [Member]
Disaggregation of Revenue [Line Items]
Revenue	550,185	447,126	1,056,189	925,160
Logistics [Member]
Disaggregation of Revenue [Line Items]
Revenue	222,449	177,293	439,484	377,495
Truck brokerage [Member]
Disaggregation of Revenue [Line Items]
Revenue	139,991	86,675	267,253	184,692
Dedicated [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 68,695	$ 68,149	$ 137,947	$ 130,755