Business Segment Information - Information by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue and property, plant and equipment by geographical area
Total revenue	$ 599.9	$ 521.1	$ 490.2	$ 461.4	$ 553.6	$ 466.6	$ 443.7	$ 431.7	$ 2,072.6	$ 1,895.6	$ 1,765.9
Long-lived assets	371.7				270.6				371.7	270.6	266.5
United States
Revenue and property, plant and equipment by geographical area
Total revenue									529.8	489.4	434.7
Long-lived assets	53.2				44.1				53.2	44.1	46.2
Germany
Revenue and property, plant and equipment by geographical area
Total revenue									213.6	201.1	200.2
Long-lived assets	175.1				137.0				175.1	137.0	140.9
Rest of Europe
Revenue and property, plant and equipment by geographical area
Total revenue									505.2	500.2	465.0
Long-lived assets	118.3				78.7				118.3	78.7	71.9
Asia Pacific
Revenue and property, plant and equipment by geographical area
Total revenue									651.0	549.2	514.8
Long-lived assets	16.4				6.3				16.4	6.3	5.4
Other
Revenue and property, plant and equipment by geographical area
Total revenue									173.0	155.7	151.2
Long-lived assets	$ 8.7				$ 4.5				$ 8.7	$ 4.5	$ 2.1