Landfill and Environmental Remediation Liabilities - Changes to Landfill and Environmental Remediation Liabilities (Detail) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Environmental Exit Cost [Line Items]
Interest accretion	$ 66	$ 65
Ending balance, environmental remediation	229
Landfill [Member]
Environmental Exit Cost [Line Items]
Beginning balance, landfill	1,443	1,421	$ 1,421
Obligations incurred and capitalized	46		54
Obligations settled	(50)		(69)
Interest accretion	66		88
Revisions in estimates and interest rate assumptions	6		(9)
Acquisitions, divestitures and other adjustments	9		(42)
Ending balance, landfill	1,520		1,443
Environmental Remediation Liabilities [Member]
Environmental Exit Cost [Line Items]
Beginning balance, environmental remediation	235	$ 227	227
Obligations settled	(15)		(21)
Interest accretion	3		5
Revisions in estimates and interest rate assumptions	7		25
Acquisitions, divestitures and other adjustments	(1)		(1)
Ending balance, environmental remediation	$ 229		$ 235