Landfill and Environmental Remediation Liabilities - Summary (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Landfill and environmental remediation liabilities
Total, Environmental Remediation	$ 248
Current (in accrued liabilities)	137	$ 165
Long-term	1,991	1,930
Total	2,128	2,095
Landfill [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Landfill	110	138
Long-term, Landfill	1,770	1,717
Total, Landfill	1,880	1,855
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Environmental Remediation	27	27
Long-term, Environmental Remediation	221	213
Total, Environmental Remediation	$ 248	$ 240