Description of Business and Summary of Accounting Policies - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 1,521,341	$ 1,289,994
Land [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	100,157	81,487
Structures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	321,283	268,723
Tractors [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	476,875	398,652
Trailers [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	354,490	305,540
Other Revenue Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	83,571	77,691
Technology Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	110,954	93,754
Other [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 74,011	$ 64,147