Landfill and Environmental Costs - Environmental Remediation Liability (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Activity in environmental remediation liabilities
Environmental remediation liabilities, beginning of year	$ 646.1	$ 697.5
Net additions charged to expense	1.6	(1.3)
Payments	(32.8)	(31.1)
Accretion expense (non-cash interest expense)	11.7	12.5
Acquisitions and other adjustments	0.1	2.8
Environmental remediation liabilities, end of period	626.7	680.4
Less: current portion	(76.4)	(76.2)
Long-term portion	$ 550.3	$ 604.2