Acquisitions - Summary of Total Purchase Price Consideration and Preliminary Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	3 Months Ended
	Aug. 01, 2015	Apr. 30, 2016	Apr. 25, 2015
Business Acquisition [Line Items]
Goodwill		$ 816,592	$ 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	35,320
Property and equipment	47,405
Identifiable intangibles	434,300
Other long-term assets	38,300
Total assets acquired	912,119
Accounts payable	122,129
Accrued liabilities and other current liabilities	21,227
Deferred tax liability	180,145
Total liabilities assumed	323,501
Identifiable net assets acquired	588,618
Goodwill	517,965
Net assets acquired	$ 1,106,583