Acquisitions - Additional Information (Detail) (National Veterinary Services Limited (NVS) [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 26, 2014
National Veterinary Services Limited (NVS) [Member]
Business Acquisition [Line Items]
Transaction costs related to the acquisition	$ 675
Acquisition contributed of net sales	$ 419,340

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration