Segment and Geographic Information, Net Sales by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 566.6	$ 512.7	$ 508.3	$ 515.5	$ 488.3	$ 349.8	$ 317.7	$ 347.2	$ 2,103.1	$ 1,503.0	$ 1,352.5
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									911.4	657.8	627.6
Reportable Geographical Components [Member] | Italy [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									211.5	94.4	44.1
Reportable Geographical Components [Member] | China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									156.0	73.7	29.3
Reportable Geographical Components [Member] | Hungary [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									153.9	145.6	145.9
Reportable Geographical Components [Member] | Austria [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									151.7	125.2	113.1
Reportable Geographical Components [Member] | Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									132.6	130.1	155.3
Reportable Geographical Components [Member] | Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									$ 386.0	$ 276.2	$ 237.2