Business, Product and Geographical Area Information and Concentration of Risk - Summary of financial information by operating segment (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	Sep. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Segment Reporting Information
Impairment of Intangible Assets									$ 2.6
Segment Operating Income (Loss):
Operating income	$ 36.9	$ 34.9	$ 34.7	$ 37.1	$ 41.9	$ 41.5	$ 12.5	$ 59.3		$ 143.6	$ 155.2	$ 181.1
Other income, net										(0.9)	0.0	(13.6)
Income before income taxes										120.0	133.0	147.2
Depreciation and Amortization:
Depreciation and amortization										43.9	39.7	36.0
Capital expenditures:
Capital expenditures										74.1	75.5	$ 76.1
Segment assets:
Total assets	$ 1,419.3				$ 1,385.2					$ 1,419.3	$ 1,385.2		$ 1,396.8