Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Jul. 27, 2019	Jul. 28, 2018
Disaggregation of Revenue [Line Items]
Net Sales	$ 270.2	$ 223.4
Goods Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Net Sales	263.0	213.6
Goods Transferred Over Time
Disaggregation of Revenue [Line Items]
Net Sales	7.2	9.8
U.S.
Disaggregation of Revenue [Line Items]
Net Sales	155.3	104.7
Malta
Disaggregation of Revenue [Line Items]
Net Sales	35.1	38.9
Canada
Disaggregation of Revenue [Line Items]
Net Sales	27.9	28.8
China
Disaggregation of Revenue [Line Items]
Net Sales	25.1	20.8
Other
Disaggregation of Revenue [Line Items]
Net Sales	26.8	30.2
Auto
Disaggregation of Revenue [Line Items]
Net Sales	186.2	175.3
Auto | Goods Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Net Sales	179.0	165.5
Auto | Goods Transferred Over Time
Disaggregation of Revenue [Line Items]
Net Sales	7.2	9.8
Auto | U.S.
Disaggregation of Revenue [Line Items]
Net Sales	100.0	77.3
Auto | Malta
Disaggregation of Revenue [Line Items]
Net Sales	27.5	30.5
Auto | Canada
Disaggregation of Revenue [Line Items]
Net Sales	21.5	20.0
Auto | China
Disaggregation of Revenue [Line Items]
Net Sales	15.6	20.8
Auto | Other
Disaggregation of Revenue [Line Items]
Net Sales	21.6	26.7
Industrial
Disaggregation of Revenue [Line Items]
Net Sales	70.8	32.2
Industrial | Goods Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Net Sales	70.8	32.2
Industrial | Goods Transferred Over Time
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Industrial | U.S.
Disaggregation of Revenue [Line Items]
Net Sales	42.5	12.1
Industrial | Malta
Disaggregation of Revenue [Line Items]
Net Sales	7.5	8.3
Industrial | Canada
Disaggregation of Revenue [Line Items]
Net Sales	6.4	8.8
Industrial | China
Disaggregation of Revenue [Line Items]
Net Sales	9.5	0.0
Industrial | Other
Disaggregation of Revenue [Line Items]
Net Sales	4.9	3.0
Interface
Disaggregation of Revenue [Line Items]
Net Sales	12.9	15.6
Interface | Goods Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Net Sales	12.9	15.6
Interface | Goods Transferred Over Time
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Interface | U.S.
Disaggregation of Revenue [Line Items]
Net Sales	12.5	15.0
Interface | Malta
Disaggregation of Revenue [Line Items]
Net Sales	0.1	0.1
Interface | Canada
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Interface | China
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Interface | Other
Disaggregation of Revenue [Line Items]
Net Sales	0.3	0.5
Medical
Disaggregation of Revenue [Line Items]
Net Sales	0.3	0.3
Medical | Goods Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Net Sales	0.3	0.3
Medical | Goods Transferred Over Time
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Medical | U.S.
Disaggregation of Revenue [Line Items]
Net Sales	0.3	0.3
Medical | Malta
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Medical | Canada
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Medical | China
Disaggregation of Revenue [Line Items]
Net Sales	0.0	0.0
Medical | Other
Disaggregation of Revenue [Line Items]
Net Sales	$ 0.0	$ 0.0