Business Acquisitions (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 1,063.5	$ 991.0
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Tangible assets acquired	21.3
Intangible assets	29.8
Goodwill	61.9
Net deferred taxes	(0.2)
Other liabilities assumed	(12.5)
TOTAL CONSIDERATION, NET OF CASH RECEIVED	$ 100.3