Landfill and Environmental Remediation Liabilities - Summary (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Landfill and environmental remediation liabilities
Total, Environmental Remediation	$ 233
Current (in accrued liabilities)	158	$ 169
Long-term	1,866	1,828
Total	2,024	1,997
Landfill [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Landfill	132	143
Long-term, Landfill	1,659	1,617
Total, Landfill	1,791	1,760
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Current (in accrued liabilities), Environmental Remediation	26	26
Long-term, Environmental Remediation	207	211
Total, Environmental Remediation	$ 233	$ 237