Revenue and Assets by Geographic Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Amount of identifiable long-lived assets (consisting of property, plant and equipment)	$ 767.9	$ 683.3
United States
Segment Reporting Information [Line Items]
Amount of identifiable long-lived assets (consisting of property, plant and equipment)	393.3	388.5
Thailand
Segment Reporting Information [Line Items]
Amount of identifiable long-lived assets (consisting of property, plant and equipment)	215.5	178.0
Various Other Countries besides United States and Thailand
Segment Reporting Information [Line Items]
Amount of identifiable long-lived assets (consisting of property, plant and equipment)	$ 159.1	$ 116.8
Located outside US, in aggregate
Geographic Areas, Revenues from External Customers [Abstract]
Percentage of net sales to unaffiliated customers	85.00%	84.00%	84.00%
Europe
Geographic Areas, Revenues from External Customers [Abstract]
Percentage of net sales to unaffiliated customers	24.00%	24.00%	22.00%
Asia
Geographic Areas, Revenues from External Customers [Abstract]
Percentage of net sales to unaffiliated customers	58.00%	58.00%	59.00%
China, including Hong-Kong
Geographic Areas, Revenues from External Customers [Abstract]
Percentage of net sales to unaffiliated customers	30.00%	32.00%	30.00%
Taiwan
Geographic Areas, Revenues from External Customers [Abstract]
Percentage of net sales to unaffiliated customers	11.00%	9.00%	12.00%