Landfill and Environmental Remediation Liabilities - Summary (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Landfill and environmental remediation liabilities
Total, Environmental Remediation	$ 250
Current (in accrued liabilities)	163	$ 147
Long-term	1,727	1,675
Total	1,890	1,822
Landfill [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Landfill	140	119
Long-term, Landfill	1,500	1,457
Total, Landfill	1,640	1,576
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Environmental Remediation	23	28
Long-term, Environmental Remediation	227	218
Total, Environmental Remediation	$ 250	$ 246