Segment and Geographic Information, Net Sales by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 556.7	$ 541.0	$ 548.9	$ 566.1	$ 566.6	$ 512.7	$ 508.3	$ 515.5	$ 2,212.7	$ 2,103.1	$ 1,503.0
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									1,032.3	911.4	657.8
Reportable Geographical Components [Member] | Italy [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									217.3	211.5	94.4
Reportable Geographical Components [Member] | China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									172.1	156.0	73.7
Reportable Geographical Components [Member] | Hungary [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									165.6	153.9	145.6
Reportable Geographical Components [Member] | Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									123.1	132.6	130.1
Reportable Geographical Components [Member] | Austria [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									116.2	151.7	125.2
Reportable Geographical Components [Member] | Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									$ 386.1	$ 386.0	$ 276.2