Landfill and Environmental Remediation Liabilities - Summary (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Landfill and environmental remediation liabilities
Total, Environmental Remediation	$ 240
Current (in accrued liabilities)	165	$ 169
Long-term	1,930	1,828
Total	2,095	1,997
Landfill [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Landfill	138	143
Long-term, Landfill	1,717	1,617
Total, Landfill	1,855	1,760
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Environmental Remediation	27	26
Long-term, Environmental Remediation	213	211
Total, Environmental Remediation	$ 240	$ 237