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Detail of Certain Balance Sheet Accounts - Property and Equipment (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]    
Land $ 48,832 $ 45,919
Buildings and leasehold improvements 155,628 137,515
Operating equipment and vehicles 1,834,715 1,634,850
Office equipment, furniture and fixtures and information technology systems 170,115 145,174
Construction work in progress 60,587 73,461
Property and equipment, gross 2,269,877 2,036,919
Less — Accumulated depreciation and amortization (981,275) (862,825)
Property and equipment, net $ 1,288,602 $ 1,174,094
Minimum | Buildings and leasehold improvements    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 5 years  
Minimum | Operating equipment and vehicles    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 5 years  
Minimum | Office equipment, furniture and fixtures and information technology systems    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 3 years  
Maximum | Buildings and leasehold improvements    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 30 years  
Maximum | Operating equipment and vehicles    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 25 years  
Maximum | Office equipment, furniture and fixtures and information technology systems    
Property, Plant and Equipment [Line Items]    
Estimated Useful Lives in Years 10 years