Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 22, 2019
Document And Entity Information [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2019  
Entity File Number 1-12154  
Entity Registrant Name WASTE MANAGEMENT INC  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 73-1309529  
Entity Address, Address Line One 1001 Fannin Street  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77002  
City Area Code 713  
Local Phone Number 512-6200  
Title of 12(b) Security Common Stock  
Trading Symbol WM  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   424,232,181
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0000823768  
Amendment Flag false