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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 |  |

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