Segment and Geographic Information - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information
Sales to external customers	$ 290.1	$ 272.2	$ 277.9	$ 244.1	$ 269.4	$ 202.7	$ 199.8	$ 171.0	$ 1,084.3	$ 842.9	$ 722.0
Property, plant and equipment, net	361.1				285.0				361.1	285.0
United States
Segment Reporting Information
Sales to external customers									604.8	475.0	378.0
Property, plant and equipment, net	176.8				166.6				176.8	166.6
Total Foreign
Segment Reporting Information
Sales to external customers									479.5	367.9	344.0
Property, plant and equipment, net	184.3				118.4				184.3	118.4
China
Segment Reporting Information
Sales to external customers									115.1	101.3	84.7
Property, plant and equipment, net	77.2				82.4				77.2	82.4
Italy
Segment Reporting Information
Property, plant and equipment, net	52.9				2.0				52.9	2.0
Czech Republic
Segment Reporting Information
Property, plant and equipment, net	21.5				20.5				21.5	20.5
India
Segment Reporting Information
Property, plant and equipment, net	19.8				0.0				19.8	0.0
Germany
Segment Reporting Information
Property, plant and equipment, net	12.9				13.4				12.9	13.4
Other foreign countries
Segment Reporting Information
Sales to external customers									364.4	266.6	$ 259.3
Property, plant and equipment, net	$ 0.0				$ 0.1				$ 0.0	$ 0.1