Deferred Revenue And Performance Obligations - Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	[1]	Sep. 28, 2018	Sep. 29, 2017	[1]
Revenue Recognition and Deferred Revenue [Abstract]
Beginning Balance of the period	$ 356.2	$ 307.3		$ 276.6	$ 246.4
Revenue recognized	(41.5)	(43.3)		(201.7)	(185.8)
Acquired deferred revenue	26.6	1.5		50.3	6.1
Net deferred revenue activity	23.0	19.4		239.1	218.2
Ending balance of the period	$ 364.3	$ 284.9		$ 364.3	$ 284.9

[1] See Note 2 for a summary of adjustments