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Asset Impairments and Unusual Items (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2019	Jun. 30, 2018
Divestitures
Investment impairment	$ 52
Disposed of by Sale, Not Discontinued Operations [Member]
Divestitures
Gain (loss) on sale of assets		$ 42

X

- Definition

Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

+ Details

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X

- Definition

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.

+ References

No definition available.

+ Details

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X

- Definition

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.

+ References

No definition available.

+ Details

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Namespace Prefix:	wm_
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X

- Details

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