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Significant Accounting Policies - Narrative - Recently Issued Accounting Pronouncements (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
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Sales	$ 249.0	$ 228.0	$ 230.1	$ 201.2	$ 219.7	$ 195.6	$ 209.3	$ 191.9	$ 908.3	$ 816.5	$ 809.1
Preproduction Tooling [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Sales									$ 10.4

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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.

+ References

No definition available.

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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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