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Significant Accounting Policies - Narrative - Financial Reporting Periods (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Apr. 28, 2018	Jan. 27, 2018	Oct. 28, 2017	Jul. 29, 2017	Apr. 29, 2017	Jan. 28, 2017	Oct. 29, 2016	Jul. 30, 2016	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Financial Reporting Periods [Line Items]
Fiscal year duration									fifty-two weeks	fifty-two weeks	fifty-two weeks
Research and Development Expense									$ 37.9	$ 27.8	$ 27.8
Net Sales	$ 249.0	$ 228.0	$ 230.1	$ 201.2	$ 219.7	$ 195.6	$ 209.3	$ 191.9	$ 908.3	$ 816.5	$ 809.1
Minimum
Financial Reporting Periods [Line Items]
Fiscal year duration									fifty-two weeks
Maximum
Financial Reporting Periods [Line Items]
Fiscal year duration									fifty-three weeks

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- Definition

[Line Items] for Financial Reporting Periods [Table]

+ References

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Fiscal Year Duration

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- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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