Landfill and Environmental Remediation Liabilities - Summary (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Landfill and environmental remediation liabilities
Total, Environmental Remediation	$ 242
Current (in accrued liabilities)	134	$ 165
Long-term	2,030	1,930
Total	2,164	2,095
Landfill [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Landfill	108	138
Long-term, Landfill	1,814	1,717
Total, Landfill	1,922	1,855
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Environmental Remediation	26	27
Long-term, Environmental Remediation	216	213
Total, Environmental Remediation	$ 242	$ 240