Landfill and Environmental Remediation Liabilities - Liabilities for Landfill and Environmental Remediation Costs (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Site Contingency [Line Items]
Total, Environmental Remediation	$ 253
Current (in accrued liabilities)	146	$ 143
Long-term	1,683	1,584
Total	1,829	1,727
Landfill [Member]
Site Contingency [Line Items]
Current (in accrued liabilities), Landfill	115	112
Long-term, Landfill	1,461	1,406
Total, Landfill	1,576	1,518
Environmental Remediation Liabilities [Member]
Site Contingency [Line Items]
Current (in accrued liabilities), Environmental Remediation	31	31
Long-term, Environmental Remediation	222	178
Total, Environmental Remediation	$ 253	$ 209