Goodwill and Purchased Intangible Assets - Goodwill (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2016	$ 3,081.7
Other	(2.3)
Balance as of June 30, 2017	$ 3,079.4