Business Acquisitions, Investments and Restructuring Charges - Acquisitions (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Purchase price:
Cash used in acquisitions, net of cash acquired	$ 178.9	$ 69.3
Excess purchase price allocated as follows:
Goodwill	11,497.7		$ 11,400.1
Series of Individually Immaterial Business Acquisitions
Purchase price:
Cash used in acquisitions, net of cash acquired	152.6	63.6
Contingent consideration	1.6	0.0
Holdbacks	14.1	8.4
Fair value, future minimum lease payments	0.7	0.0
Total	169.0	72.0
Allocated as follows:
Accounts receivable	7.3	1.5
Landfill airspace	0.0	22.2
Property and equipment	36.6	12.1
Other assets	5.3	0.1
Inventory	0.0	0.2
Accounts payable	(3.0)	(0.3)
Closure and post-closure liabilities	0.0	(1.7)
Other liabilities	(5.5)	(3.9)
Fair value of tangible assets acquired and liabilities assumed	40.7	30.2
Excess purchase price allocated as follows:
Other intangible assets	28.4	10.5
Goodwill	99.9	31.3
Total allocated	$ 128.3	$ 41.8