Landfill and Environmental Remediation Liabilities - Changes (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Landfill and environmental remediation liabilities
Interest accretion	$ 53	$ 49
Ending balance, environmental remediation	220
Landfill [Member]
Landfill and environmental remediation liabilities
Beginning balance, landfill	2,156
Obligations incurred and capitalized	57
Obligations settled	(44)
Interest accretion	53
Revisions in estimates and interest rate assumptions	11
Acquisitions, divestitures and other adjustments	1
Ending balance, landfill	2,234
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Beginning balance, environmental remediation	230
Obligations settled	(9)
Interest accretion	1
Revisions in estimates and interest rate assumptions	(2)
Ending balance, environmental remediation	$ 220

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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