Goodwill and Purchased Intangible Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Reportable_Segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 2,981.3	$ 2,981.5
Other		(0.2)
Additions due to business combinations	100.4
Goodwill, end of period	$ 3,081.7	2,981.3	$ 2,981.5
Number of reporting units | Reportable_Segment	3
Impairment of goodwill	$ 0.0	$ 0.0	$ 850.0