Balance Sheet Information - Periodic Pension Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Balance Sheet Related Disclosures [Abstract]
Service cost	$ 2.4	$ 2.4	$ 7.3	$ 7.0
Interest cost	1.2	1.1	3.6	3.2
Expected return on plan assets	(1.5)	(1.4)	(4.6)	(4.0)
Total net periodic pension cost	$ 2.1	$ 2.1	$ 6.3	$ 6.2