Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 157,790	$ 162,914
Less: accumulated depreciation and amortization	(100,354)	(97,250)
Property and equipment, net	57,436	65,664
Transportation Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	48,835	48,879
Computer Equipment And Purchased Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	60,692	64,615
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,871	11,649
Leaseholds Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	27,737	28,211
Internally Developed Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 9,655	$ 9,560