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v3.20.4

Summary of Significant Accounting Policies - Intangibles (Detail) | 12 Months Ended
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Dec. 31, 2020
Customer and supplier relationships [Member] | Minimum [Member] |
Significant accounting policies |
Amortizable period of the intangible assets | 10 years
Customer and supplier relationships [Member] | Maximum [Member] |
Significant accounting policies |
Amortizable period of the intangible assets | 15 years
Covenants not-to-compete [Member] |
Significant accounting policies |
Amortizable period of the intangible assets | 5 years

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- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | wm_SignificantAccountingPoliciesLineItems
Namespace Prefix: | wm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=wm_CustomerAndSupplierRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |