Goodwill and Purchased Intangible Assets (Details) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) Reportable_Segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning of period				$ 4,057.7	$ 2,981.5	$ 4,057.7
Additions due to business combination						13.6
Impairment	$ (850.0)	$ 0.0	$ 0.0	$ 0.0	0.0	(850.0)	$ 0.0
Divestiture						(239.8)
Other					(0.2)
Goodwill, end of period	$ 2,981.5				$ 2,981.3	$ 2,981.5	$ 4,057.7
Number of reporting units | Reportable_Segment					3