Goodwill (Rollforward of Goodwill) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Goodwill [Roll Forward]
As of January, 1	$ 17,888.2	$ 4,147.8
Acquisitions	1,076.2	8,834.3
Foreign currency translation	517.7	(19.7)
As of June 30,	$ 19,482.1	$ 12,962.4