Landfill and Environmental Remediation Liabilities - Changes (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Landfill and environmental remediation liabilities
Interest accretion	$ 98	$ 95	$ 92
Ending balance, environmental remediation	240
Landfill [Member]
Landfill and environmental remediation liabilities
Beginning balance, landfill	1,760
Obligations incurred and capitalized	72
Obligations settled	(113)
Interest accretion	98
Revisions in estimates and interest rate assumptions	33
Acquisitions, divestitures and other adjustments	5
Ending balance, landfill	$ 1,855	$ 1,760
Risk-free discount rate of the obligations	1.75%	2.75%	2.50%
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Beginning balance, environmental remediation	$ 237
Obligations settled	(22)
Interest accretion	4
Revisions in estimates and interest rate assumptions	21
Ending balance, environmental remediation	$ 240	$ 237
Risk-free discount rate of the obligations	1.75%	2.75%
Increase (decrease) operating expenses due to change in discount rate	$ 11

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

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