Acquisitions - Summary of Total Purchase Price Consideration and Preliminary Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($)
$ in Thousands
 3 Months Ended
Aug. 01, 2015
Jan. 30, 2016
Jun. 16, 2015
Apr. 25, 2015
Business Acquisition [Line Items]        
Goodwill   $ 815,316   $ 299,924
Animal Health International [Member]        
Business Acquisition [Line Items]        
Total purchase price consideration $ 1,106,583      
Receivables 161,427      
Inventory 195,367      
Prepaid expenses and other current assets 33,005      
Property and equipment 44,178      
Identifiable intangibles 434,300   $ 434,300  
Other long-term assets 40,869      
Total assets acquired 909,146      
Accounts payable 122,129      
Accrued liabilities and other current liabilities 21,015      
Deferred tax liability 177,789      
Total liabilities assumed 320,933      
Identifiable net assets acquired 588,213      
Goodwill 518,370      
Net assets acquired $ 1,106,583