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Commitments and Contingencies - Additional Information (Detail)
$ in Millions
 1 Months Ended 9 Months Ended
Oct. 31, 2017
Tractor
Nov. 30, 2016
USD ($)
Container
Sep. 30, 2017
USD ($)
Tractor
Container
Oct. 21, 2017
Container
Loss Contingencies [Line Items]        
Purchase contract units, containers   4,000    
Cost of purchasing containers | $   $ 40    
Number of containers expected to be receive in remainder of fiscal year     394  
Number of containers expected to be receive in year two     1,450  
Purchase contract units tractors | Tractor     154  
Cost of purchasing tractors | $     $ 18  
Subsequent Event [Member]        
Loss Contingencies [Line Items]        
Number of containers received       2,156
Purchase contract units tractors | Tractor 38