Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The aggregate amount of asset impairment charges, (gains) and losses related to the divestiture of businesses and unusual items incurred during an accounting period.

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The amount by which the fair value of an investment is less than the carrying amount of that investment and the decline in fair value is deemed to be other than temporary.

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Asset Impairments and Unusual Items - Quarter (Detail) - USD ($) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Asset Impairments and Unusual Items
(Gain) loss from divestitures, asset impairments and unusual items, net	$ 7			$ 1		$ 68	$ 8
Asset impairments		$ 61
Investment impairment					$ 52			$ 52
Refined Coal Facility [Member]
Asset Impairments and Unusual Items
Equity method investments impairment charges			$ 7			$ 7
Landfills and Oil Field Waste Injection Facility [Member]
Asset Impairments and Unusual Items
Asset impairments		41
Asset fair value		8
Energy Services Assets [Member]
Asset Impairments and Unusual Items
Asset fair value		239
Energy Services Assets [Member] \| Tier 1 [Member]
Asset Impairments and Unusual Items
Asset impairments		41
Renewable Energy Assets [Member]
Asset Impairments and Unusual Items
Asset impairments	$ 7
Landfill [Member]
Asset Impairments and Unusual Items
Asset impairments		20
Landfill [Member] \| Carrying Value [Member]
Asset Impairments and Unusual Items
Asset impairments		12
Landfill [Member] \| Expected Timing [Member]
Asset Impairments and Unusual Items
Asset impairments		$ 8