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Environmnetal Matters - Narrative (Details) $ in Millions | 12 Months Ended
--- | ---
Apr. 28, 2018 USD ($) | Apr. 29, 2017 USD ($) | Apr. 30, 2016 USD ($)
Site Contingency [Line Items] |  |  |
Number of plant sites subject to environmental investigation and/or remediation | 2 |  |
Accruals for environmental matters | $ 1.1 | $ 1.3 |
Spent on remediation clean-ups and related studies | 0.3 | 1.2 | $ 1.0
Other accrued expenses |  |  |
Site Contingency [Line Items] |  |  |
Accruals for environmental matters | $ 0.8 | $ 0.8 |

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 + Details
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