Schedule Of Revenue By Major Customers By Reporting Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 4,132,981	$ 4,084,577	$ 4,615,144
BCO Independent Contractors – Truck
Disaggregation of Revenue [Line Items]
Percentage of Consolidated Revenue	45.00%	45.00%	43.00%
Brokerage Carriers - Truck
Disaggregation of Revenue [Line Items]
Percentage of Consolidated Revenue	47.00%	47.00%	49.00%
Rail Intermodal
Disaggregation of Revenue [Line Items]
Percentage of Consolidated Revenue	3.00%	3.00%	3.00%
Ocean and air cargo carriers
Disaggregation of Revenue [Line Items]
Percentage of Consolidated Revenue	3.00%	3.00%	3.00%
BCO Independent Contractor Truck and Brokerage Carriers Truck | Van Equipment
Disaggregation of Revenue [Line Items]
Revenue	$ 2,515,940	$ 2,371,188	$ 2,791,494
BCO Independent Contractor Truck and Brokerage Carriers Truck | Unsided/Platform Equipment
Disaggregation of Revenue [Line Items]
Revenue	1,202,295	1,295,817	1,386,387
BCO Independent Contractor Truck and Brokerage Carriers Truck | Less than Truckload
Disaggregation of Revenue [Line Items]
Revenue	$ 97,546	$ 98,324	$ 102,531