Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jan. 24, 2015	Apr. 26, 2014
Inventories
Raw materials	$ 78,359us-gaap_InventoryRawMaterials	$ 71,247us-gaap_InventoryRawMaterials
Work in process	14,408us-gaap_InventoryWorkInProcess	13,722us-gaap_InventoryWorkInProcess
Finished goods	93,569us-gaap_InventoryFinishedGoods	91,842us-gaap_InventoryFinishedGoods
FIFO inventories	186,336us-gaap_InventoryGross	176,811us-gaap_InventoryGross
Excess of FIFO over LIFO	(26,203)us-gaap_InventoryLIFOReserve	(29,802)us-gaap_InventoryLIFOReserve
Inventories, net	$ 160,133us-gaap_InventoryNet	$ 147,009us-gaap_InventoryNet

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

+ References

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-Publisher SEC

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-Number 210

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-Subparagraph (SX 210.5-02.6(a)(1))

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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

+ References

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Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

+ References

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

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-Subparagraph (SX 210.5-02.6(a))

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 35

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Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(3))

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