SEGMENT INFORMATION - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 29, 2016	Oct. 31, 2015	Oct. 29, 2016	Oct. 31, 2015
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers	$ 209.3	$ 208.4	$ 401.1	$ 411.7
Income (loss) from operations	29.1	26.4	55.6	56.9
Interest income, net	(0.1)	(0.3)	(0.1)	(0.5)
Other income, net	(1.9)	(0.2)	(1.9)	(0.5)
Income before income taxes	31.1	26.9	57.6	57.9
Operating Segments
Segment Reporting Information [Line Items]
Net sales	209.3	208.4	401.1	411.7
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	164.2	160.8	311.3	313.8
Income (loss) from operations	38.4	35.1	74.5	71.1
Automotive | Operating Segments
Segment Reporting Information [Line Items]
Net sales	166.6	163.1	315.3	317.9
Automotive | Transfers between segments
Segment Reporting Information [Line Items]
Net sales	(2.4)	(2.3)	(4.0)	(4.1)
Interface
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers	32.5	35.8	65.2	69.6
Income (loss) from operations	(0.4)	1.4	(1.3)	2.1
Interface | Operating Segments
Segment Reporting Information [Line Items]
Net sales	33.0	36.0	65.9	70.1
Interface | Transfers between segments
Segment Reporting Information [Line Items]
Net sales	(0.5)	(0.2)	(0.7)	(0.5)
Power Products
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers	12.5	11.8	24.5	28.3
Income (loss) from operations	2.1	0.5	4.5	3.5
Power Products | Operating Segments
Segment Reporting Information [Line Items]
Net sales	12.5	11.8	24.6	28.3
Power Products | Transfers between segments
Segment Reporting Information [Line Items]
Net sales	0.0	0.0	(0.1)	0.0
Other
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers	0.1	0.0	0.1	0.0
Income (loss) from operations	(2.3)	(1.9)	(4.7)	(4.1)
Other | Operating Segments
Segment Reporting Information [Line Items]
Net sales	1.6	0.0	2.0	0.1
Other | Transfers between segments
Segment Reporting Information [Line Items]
Net sales	(1.5)	0.0	(1.9)	(0.1)
Eliminations/Corporate
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers	0.0	0.0	0.0	0.0
Income (loss) from operations	(8.7)	(8.7)	(17.4)	(15.7)
Eliminations/Corporate | Operating Segments
Segment Reporting Information [Line Items]
Net sales	(4.4)	(2.5)	(6.7)	(4.7)
Eliminations/Corporate | Transfers between segments
Segment Reporting Information [Line Items]
Net sales	$ 4.4	$ 2.5	$ 6.7	$ 4.7