Goodwill (Goodwill Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
As of January 1,	$ 4,147.8	$ 2,474.9
Acquisitions	14,124.5	1,700.1
Foreign currency translation	(384.1)	(27.2)
As of December 31,	$ 17,888.2	$ 4,147.8