Integration and Acquisition Costs (Summary of Employee Termination Related Reserve and Other) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
As of January 1,	$ 74.0	$ 0.0
Amount charged to integration costs	247.9	267.3
Paid/utilized	(192.4)	(193.3)
As of December 31,	129.5	74.0
Severance and employee benefits
Restructuring Reserve [Roll Forward]
As of January 1,	74.0	0.0
Amount charged to integration costs	175.2	267.3
Paid/utilized	(176.3)	(193.3)
As of December 31,	72.9	74.0
Lease terminations
Restructuring Reserve [Roll Forward]
As of January 1,	0.0	0.0
Amount charged to integration costs	72.7	0.0
Paid/utilized	(16.1)	0.0
As of December 31,	$ 56.6	$ 0.0