Acquisition of Oakleaf Global Holdings (Details 2) (USD $) In Millions, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pro forma consolidated results of operations
Operating revenues	$ 3,566	$ 3,379	$ 10,287	$ 9,740
Net income attributable to Waste Management Inc.	$ 272	$ 239	$ 689	$ 660
Basic earnings per common share	$ 0.58	$ 0.50	$ 1.46	$ 1.37
Diluted earnings per common share	$ 0.58	$ 0.50	$ 1.45	$ 1.36

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph r(2, 3)

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 54

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 55

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