Goodwill (Rollforward of Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Goodwill [Roll Forward]
As of January, 1	$ 17,888.2	$ 4,147.8
Acquisitions	1,213.8	2,729.5
Foreign currency translation	47.1	4.6
As of March 31,	$ 19,149.1	$ 6,881.9