v2.4.0.6
Document and Company Information (USD $)
9 Months Ended
Sep. 30, 2009
Oct. 26, 2009
Jun. 30, 2008
Document and Company Information [Abstract]      
Entity Registrant Name WASTE MANAGEMENT INC    
Entity Central Index Key 0000823768    
Document Type 10-Q    
Document Period End Date Sep. 30, 2009    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 18,463,749,815
Entity Common Stock, Shares Outstanding (actual number)   489,651,990