Landfill and Environmental Costs - Narrative (Details) $ in Millions, ft³ in Billions	6 Months Ended
	Jun. 30, 2016 USD ($) landfill ft³	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Environmental Exit Cost [Line Items]
Number of active solid waste landfills | landfill	193
Total available disposal capacity (billion in-place cubic feet) | ft³	135
Number of closed landfills | landfill	125
Fair value of assets that are legally restricted for final capping, closure and post-closure obligations	$ 27.6		$ 27.3
Amount of aggregate potential remediation liability	350.0
Payments for management and monitoring of remediation area	32.8	$ 31.1
Remediation liability	626.7	$ 680.4	$ 646.1	$ 697.5
Bridgeton Landfill
Environmental Exit Cost [Line Items]
Payments for management and monitoring of remediation area	11.8
Remediation liability	205.7
Remediation liability expected to be paid during the remainder of 2016	13.0
Bridgeton Landfill | Maximum
Environmental Exit Cost [Line Items]
Range of loss for remediation costs (maximum)	$ 164.0