Business Acquisitions, Investments and Restructuring Charges - Acquisitions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Purchase price:
Cash used in acquisitions, net of cash acquired	$ 62.7	$ 19.1
Excess purchase price allocated as follows:
Goodwill	11,431.6		$ 11,400.1
Waste Business Acquisitions
Purchase price:
Cash used in acquisitions, net of cash acquired	50.6	17.1
Holdbacks	3.9	2.9
Total	54.5	20.0
Allocated as follows:
Accounts receivable	1.6	0.7
Property and equipment	7.7	7.3
Other assets	0.4	0.0
Other liabilities	(0.4)	(3.1)
Fair value of tangible assets acquired and liabilities assumed	9.3	4.9
Excess purchase price allocated as follows:
Other intangible assets	12.7	1.2
Goodwill	32.5	13.9
Total allocated	$ 45.2	$ 15.1