Basis of Presentation (Policies)	3 Months Ended
Jun. 30, 2012
Basis of Presentation [Abstract]
Basis of Presentation	The financial statements presented in this report represent the consolidation of Waste Management, Inc., a Delaware corporation; Waste Management’s wholly-owned and majority-owned subsidiaries; and certain variable interest entities for which Waste Management or its subsidiaries are the primary beneficiary as described in Note 13. Waste Management is a holding company and all operations are conducted by its subsidiaries. When the terms “the Company,” “we,” “us” or “our” are used in this document, those terms refer to Waste Management, Inc., its consolidated subsidiaries and consolidated variable interest entities. When we use the term “WM,” we are referring only to Waste Management, Inc., the parent holding company. We currently manage and evaluate our principal operations through five Groups. Our four geographic operating Groups, which are comprised of our Eastern, Midwest, Southern and Western Groups, provide collection, transfer, disposal (in both solid waste and hazardous waste landfills) and recycling services. Our fifth Group is the Wheelabrator Group, which provides waste-to-energy services and manages waste-to-energy facilities and independent power production plants. We also provide additional services that are not managed through our five Groups, including the operations of Oakleaf Global Holdings acquired on July 28, 2011 (“Oakleaf”), which are presented in this report as “Other.” Additional information related to our segments and to our acquisition of Oakleaf can be found in Note 8 and in Note 9, respectively. The Condensed Consolidated Financial Statements as of June 30, 2012 and for the three and six months ended June 30, 2012 and 2011 are unaudited. In the opinion of management, these financial statements include all adjustments, which, unless otherwise disclosed, are of a normal recurring nature, necessary for a fair presentation of the financial position, results of operations, and cash flows for the periods presented. The results for interim periods are not necessarily indicative of results for the entire year. The financial statements presented herein should be read in connection with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2011. In preparing our financial statements, we make numerous estimates and assumptions that affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision from data available or simply cannot be readily calculated based on generally accepted methods. In some cases, these estimates are particularly difficult to determine and we must exercise significant judgment. In preparing our financial statements, the most difficult, subjective and complex estimates and the assumptions that present the greatest amount of uncertainty relate to our accounting for landfills, environmental remediation liabilities, asset impairments, deferred income taxes and reserves associated with our insured and self-insured claims. Actual results could differ materially from the estimates and assumptions that we use in the preparation of our financial statements.
Fair Value Measurement	Fair Value Measurement — In May 2011, the Financial Accounting Standards Board (“FASB”) amended authoritative guidance associated with fair value measurements. This amended guidance defines certain requirements for measuring fair value and for disclosing information about fair value measurements in accordance with U.S. generally accepted accounting principles. The amendments to authoritative guidance associated with fair value measurements were effective for the Company on January 1, 2012 and have been applied prospectively. The adoption of this guidance did not have a material impact on our consolidated financial statements.
Comprehensive Income	Comprehensive Income — In June 2011, the FASB issued amended authoritative guidance associated with comprehensive income, which requires companies to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. This update eliminates the option to present the components of other comprehensive income as part of the statement of changes in equity. In December 2011, the FASB deferred the effective date of the specific requirement to present items that are reclassified out of accumulated other comprehensive income to net income alongside their respective components of net income and other comprehensive income. The amendments to authoritative guidance associated with comprehensive income were effective for the Company on January 1, 2012 and have been applied retrospectively. The adoption of this guidance did not have a material impact on our consolidated financial statements.

Basis of Presentation (Policies)

3 Months Ended

Jun. 30, 2012

The financial statements presented in this report represent the consolidation of Waste Management, Inc., a Delaware corporation; Waste Management’s wholly-owned and majority-owned subsidiaries; and certain variable interest entities for which Waste Management or its subsidiaries are the primary beneficiary as described in Note 13. Waste Management is a holding company and all operations are conducted by its subsidiaries. When the terms “the Company,” “we,” “us” or “our” are used in this document, those terms refer to Waste Management, Inc., its consolidated subsidiaries and consolidated variable interest entities. When we use the term “WM,” we are referring only to Waste Management, Inc., the parent holding company.

We currently manage and evaluate our principal operations through five Groups. Our four geographic operating Groups, which are comprised of our Eastern, Midwest, Southern and Western Groups, provide collection, transfer, disposal (in both solid waste and hazardous waste landfills) and recycling services. Our fifth Group is the Wheelabrator Group, which provides waste-to-energy services and manages waste-to-energy facilities and independent power production plants. We also provide additional services that are not managed through our five Groups, including the operations of Oakleaf Global Holdings acquired on July 28, 2011 (“Oakleaf”), which are presented in this report as “Other.” Additional information related to our segments and to our acquisition of Oakleaf can be found in Note 8 and in Note 9, respectively.

The Condensed Consolidated Financial Statements as of June 30, 2012 and for the three and six months ended June 30, 2012 and 2011 are unaudited. In the opinion of management, these financial statements include all adjustments, which, unless otherwise disclosed, are of a normal recurring nature, necessary for a fair presentation of the financial position, results of operations, and cash flows for the periods presented. The results for interim periods are not necessarily indicative of results for the entire year. The financial statements presented herein should be read in connection with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2011.

In preparing our financial statements, we make numerous estimates and assumptions that affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision from data available or simply cannot be readily calculated based on generally accepted methods. In some cases, these estimates are particularly difficult to determine and we must exercise significant judgment. In preparing our financial statements, the most difficult, subjective and complex estimates and the assumptions that present the greatest amount of uncertainty relate to our accounting for landfills, environmental remediation liabilities, asset impairments, deferred income taxes and reserves associated with our insured and self-insured claims. Actual results could differ materially from the estimates and assumptions that we use in the preparation of our financial statements.

Fair Value Measurement

Fair Value Measurement — In May 2011, the Financial Accounting Standards Board (“FASB”) amended authoritative guidance associated with fair value measurements. This amended guidance defines certain requirements for measuring fair value and for disclosing information about fair value measurements in accordance with U.S. generally accepted accounting principles. The amendments to authoritative guidance associated with fair value measurements were effective for the Company on January 1, 2012 and have been applied prospectively. The adoption of this guidance did not have a material impact on our consolidated financial statements.

Comprehensive Income

Comprehensive Income — In June 2011, the FASB issued amended authoritative guidance associated with comprehensive income, which requires companies to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. This update eliminates the option to present the components of other comprehensive income as part of the statement of changes in equity. In December 2011, the FASB deferred the effective date of the specific requirement to present items that are reclassified out of accumulated other comprehensive income to net income alongside their respective components of net income and other comprehensive income. The amendments to authoritative guidance associated with comprehensive income were effective for the Company on January 1, 2012 and have been applied retrospectively. The adoption of this guidance did not have a material impact on our consolidated financial statements.