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Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit

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Entity Wide Revenue Criteria For Major Customer Percentage Of Revenue

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Income tax benefit on cash flow hedge loss.

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Percentage Of Liability Recorded.

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Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of asset related to consideration paid in advance for other costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Percentage of fair value of reporting unit in excess of carrying amount.

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Summary of Significant Accounting Policies - Additional Information (Details) shares in Thousands	3 Months Ended	12 Months Ended
	Apr. 29, 2017 USD ($)	Apr. 29, 2017 USD ($) reporting_unit Segment shares	Apr. 30, 2016 USD ($) shares	Apr. 25, 2015 USD ($) shares
Accounting Policies [Abstract]
Number of reportable segments \| Segment		3
Maturity period of maximum (in days)		90 days
Inventories valued at LIFO as % of total inventories	84.00%	84.00%	84.00%
Accumulated LIFO reserve	$ 77,816,000	$ 77,816,000	$ 76,501,000
Property, Plant and Equipment [Line Items]
Number of reporting units \| reporting_unit		2
Goodwill impairment	0
Asset impairment charges		$ 36,312,000	0	$ 0
Consolidated net sales, percentage		10.00%
Percentage of liability recorded		87.00%
Total advertising and promotional expenses		$ 10,128,000	12,113,000	10,181,000
Deferred direct-marketing expenses included in prepaid and other current assets	$ 0	0	0
The income tax expense (benefit) related to cash flow hedge losses		$ 1,057,000	$ 883,000	$ (10,843,000)
Securities excluded from calculation of diluted earnings per share (in shares) \| shares		1,133	765	147
Excess tax benefit related to share-based payments		$ 2,493,000
Animal Health [Member] \| Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Percentage of fair value in excess of book value	11.00%	11.00%
Building [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		39 years
Computer Hardware And Software [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		3 years
Computer Hardware And Software [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		10 years
Office Furniture And Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		5 years
Office Furniture And Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		10 years