SEGMENT INFORMATION - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jan. 27, 2018	Jan. 28, 2017	Jan. 27, 2018	Jan. 28, 2017
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	$ 228.0	$ 195.6	$ 659.3	$ 596.7
Income (Loss) from Operations	35.6	29.1	90.7	84.8
Interest Expense (Income), Net	0.3	(0.2)	0.3	(0.3)
Other Income, Net	(3.8)	(1.0)	(2.6)	(2.9)
Income before Income Taxes	39.1	30.3	93.0	88.0
Operating Segments
Segment Reporting Information [Line Items]
Net Sales	228.0	195.6	659.3	596.7
Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	0.0	0.0	0.0	0.0
Automotive
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	184.9	150.4	528.1	461.6
Income (Loss) from Operations	39.4	36.9	118.1
Automotive \| Operating Segments
Segment Reporting Information [Line Items]
Net Sales	187.7	152.7	535.4	467.9
Income (Loss) from Operations				111.2
Automotive \| Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	(2.8)	(2.3)	(7.3)	(6.3)
Interface
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	27.9	29.8	86.3	94.9
Income (Loss) from Operations	1.8	1.3	4.0
Interface \| Operating Segments
Segment Reporting Information [Line Items]
Net Sales	28.0	29.8	86.4	95.6
Income (Loss) from Operations				(0.1)
Interface \| Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	(0.1)	0.0	(0.1)	(0.7)
Power Products
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	15.2	15.4	44.8	39.9
Income (Loss) from Operations	3.0	3.2	9.3
Power Products \| Operating Segments
Segment Reporting Information [Line Items]
Net Sales	15.2	15.4	44.9	40.0
Income (Loss) from Operations				7.7
Power Products \| Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	0.0	0.0	(0.1)	(0.1)
Other
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	0.1	0.1	0.2	0.2
Income (Loss) from Operations	(2.3)	(3.3)	(8.1)
Other \| Operating Segments
Segment Reporting Information [Line Items]
Net Sales	0.1	0.1	0.2	2.1
Income (Loss) from Operations				(8.0)
Other \| Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	0.0	0.0	0.0	(1.9)
Eliminations/Corporate
Segment Reporting Information [Line Items]
Net Sales to Unaffiliated Customers	(0.1)	(0.1)	(0.1)	0.1
Income (Loss) from Operations	(6.3)	(9.0)	(32.6)	(26.0)
Eliminations/Corporate \| Operating Segments
Segment Reporting Information [Line Items]
Net Sales	(3.0)	(2.4)	(7.6)	(8.9)
Eliminations/Corporate \| Transfers between Segments
Segment Reporting Information [Line Items]
Net Sales	$ 2.9	$ 2.3	$ 7.5	$ 9.0

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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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)
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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)
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