Landfill and Environmental Remediation Liabilities (Details 1) (USD $) In Millions	9 Months Ended	12 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Changes to landfill and environmental remediation liabilities
Ending Balance	$ 1,597	$ 1,550
Ending Balance	285
Landfill Liabilities [Member]
Changes to landfill and environmental remediation liabilities
Beginning Balance, Landfill	1,266	1,267
Obligations incurred and capitalized	36	47
Obligations settled	(56)	(86)
Interest accretion	62	82
Revisions in cost estimates and interest rate assumptions	4	(49)
Acquisitions, divestitures and other adjustments	0	5
Ending Balance	1,312	1,266
Environmental Remediation Liabilities [Member]
Changes to landfill and environmental remediation liabilities
Beginning Balance, Landfill	284
Beginning Balance, Environmental Remediation	284	256
Obligations incurred and capitalized	0	0
Obligations settled	(25)	(36)
Interest accretion	5	5
Revisions in cost estimates and interest rate assumptions	22	61
Acquisitions, divestitures and other adjustments	(1)	(2)
Ending Balance	285	284
Ending Balance	$ 285	$ 284

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 96-1

-Paragraph 161

-Subparagraph a

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The increase (decrease) in the accrual for environmental loss in the period from revisions in estimates to existing obligations. The amount does not relate to changes in the environmental accrual related to business acquisitions or divestitures, or to currency movements.

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForRevisionInEstimates
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate amount disbursed during the reporting period to settle environmental loss contingencies.

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesPayments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 3, 10, 22

+ Details

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accretion expense recognized in the income statement during the period that is associated with asset retirement obligations. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. Such accretion expense representing changes in the liability for an asset retirement obligation due to passage of time is the result of applying an interest method of allocation to the amount of the liability at the beginning of the period. The interest rate used to measure that change shall be the credit-adjusted risk-free rate that existed when the liability, or portion thereof, was initially measured. That amount shall be recognized as an increase in the carrying amount of the liability and as an expense classified as an operating item in the statement of income. Accretion expense shall not be considered to be interest cost for purposes of capitalization of interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 13, 14

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(3)

+ Details

Name:	us-gaap_AssetRetirementObligationAccretionExpense
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of asset retirement obligations incurred during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(1)

+ Details

Name:	us-gaap_AssetRetirementObligationLiabilitiesIncurred
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of the increase (decrease) in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(4)

+ Details

Name:	us-gaap_AssetRetirementObligationRevisionOfEstimate
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Accrual for Environmental Loss Contingencies, Increase (Decrease) for Acquisitions, Divestitures and Other Adjustments, including foreign currency translation.

+ Details

Name:	wm_AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForAcquisitionsDivestituresAndOtherAdjustments
Namespace Prefix:	wm
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Accrual for Environmental Loss Contingencies, Interest Accretion.

+ Details

Name:	wm_AccrualForEnvironmentalLossContingenciesInterestAccretion
Namespace Prefix:	wm
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Asset Retirement Obligation, Adjustments for Acquisitions, Divestitures and Other Items. Includes foreign currency translation.

+ Details

Name:	wm_AssetRetirementObligationAdjustmentsForAcquisitionsDivestituresAndOtherItems
Namespace Prefix:	wm
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of asset retirement obligations settled, or otherwise disposed of, during the period.

+ Details

Name:	wm_AssetRetirementObligationLiabilitiesSettledLandfill
Namespace Prefix:	wm
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Changes to landfill and environmental remediation liabilities.

+ Details

Name:	wm_ChangesToLandfillAndEnvironmentalRemediationLiabilitiesAbstract
Namespace Prefix:	wm
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration