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Asset Impairments and Unusual Items (Detail) $ in Millions | 3 Months Ended
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Mar. 31, 2019 USD ($)
Asset Impairments and Unusual Items |
Investment impairment | $ 52

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- References No definition available. + Details
Name: | us-gaap_ExtraordinaryAndUnusualItemsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- 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
Name: | wm_InvestmentWithoutReadilyDeterminableFairValueOtherThanTemporaryImpairment
Namespace Prefix: | wm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration