Landfill and Environmental Remediation Liabilities - Liabilities for Landfill and Environmental Remediation Costs (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Site Contingency [Line Items]
Total, Environmental Remediation	$ 245
Current (in accrued liabilities)	164	$ 147
Long-term	1,712	1,675
Total	1,876	1,822
Landfill [Member]
Site Contingency [Line Items]
Current (in accrued liabilities), Landfill	138	119
Long-term, Landfill	1,493	1,457
Total, Landfill	1,631	1,576
Environmental Remediation Liabilities [Member]
Site Contingency [Line Items]
Current (in accrued liabilities), Environmental Remediation	26	28
Long-term, Environmental Remediation	219	218
Total, Environmental Remediation	$ 245	$ 246