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Landfill and Environmental Remediation Liabilities - Changes (Detail) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019
Landfill and environmental remediation liabilities |  |  |
Interest accretion | $ 49 | $ 47 |
Ending balance, environmental remediation | 242 |  |
Landfill [Member] |  |  |
Landfill and environmental remediation liabilities |  |  |
Beginning balance, landfill | 1,855 |  |
Obligations incurred and capitalized | 40 |  |
Obligations settled | (47) |  |
Interest accretion | 49 |  |
Revisions in estimates and interest rate assumptions | 27 |  |
Acquisitions, divestitures and other adjustments | (2) |  |
Ending balance, landfill | 1,922 |  |
Asset retirement obligation revision of estimate increase (decrease) related to estimated capping activities | 10 |  |
Asset retirement obligation, increase (decrease) related to landfill closure | 8 |  |
Environmental Remediation Liabilities [Member] |  |  |
Landfill and environmental remediation liabilities |  |  |
Beginning balance, environmental remediation | 240 |  |
Obligations settled | (11) |  |
Interest accretion | 1 |  |
Revisions in estimates and interest rate assumptions | 12 |  |
Ending balance, environmental remediation | 242 |  |
Increase (decrease) operating expenses due to change in discount rate | $ 12 |  |
Risk-free discount rate of the obligations | 0.75% |  | 1.75%

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- Definition Amount of expense for newly incurred environmental loss contingencies. Includes, but is not limited to, remediation expense and interest accretion. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q2) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 + Details
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- Definition Rate applied to the undiscounted amount of environmental loss contingencies to arrive at the present value recorded as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.Y.Q1) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 + Details
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