v2.3.0.15
Document And Entity Information (USD $)
12 Months Ended
Aug. 28, 2011
Sep. 30, 2011
Feb. 11, 2011
Document And Entity Information   
Document Type10-K  
Document Period End DateAug. 28, 2011
Amendment Flagfalse  
Document Fiscal Year Focus2011  
Document Fiscal Period FocusFY  
Entity Registrant NameCOSTCO WHOLESALE CORP /NEW  
Entity Central Index Key0000909832  
Entity Current Reporting StatusYes  
Entity Voluntary FilersNo  
Current Fiscal Year End Date--08-28  
Entity Filer CategoryLarge Accelerated Filer  
Entity Well-known Seasoned IssuerYes  
Entity Common Stock, Shares Outstanding 433,365,150 
Entity Public Float  $ 32,525,998,477