Landfill and Environmental Remediation Liabilities - Changes to Landfill and Environmental Remediation Liabilities (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Environmental Exit Cost [Line Items]
Increase (decrease) related to year-end review of landfill capping closure and post closure obligations included in landfill liabilities	$ 2	$ (20)
Risk-free discount rate of the obligations	2.00%	3.00%	1.75%
Increase (Decrease) to operating expenses due to change in discount rate used to estimate the present value of environmental remediation obligations	13	(18)
Landfill [Member]
Environmental Exit Cost [Line Items]
Increase (decrease) related to year-end review of landfill capping closure and post closure obligations included in landfill liabilities		23
Number of assets closed		2
Wheelabrator [Member]
Environmental Exit Cost [Line Items]
Landfill liabilities as a result of divestitures	$ 25