Operating Property (Detail) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Land	$ 15,259	$ 15,259
Buildings and improvements	57,758	56,413
Trailing equipment	363,377	342,813
Other equipment	58,317	48,732
Total operating property, gross	494,711	463,217
Less accumulated depreciation and amortization	218,700	190,374
Total operating property, net	$ 276,011	$ 272,843