v2.4.0.6
Document and Entity Information (USD $)
12 Months Ended
Sep. 02, 2012
Oct. 05, 2012
Feb. 10, 2012
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Sep. 02, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
Trading Symbol COST    
Entity Registrant Name COSTCO WHOLESALE CORP /NEW    
Entity Central Index Key 0000909832    
Current Fiscal Year End Date --09-02    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   432,424,379  
Entity Public Float     $ 36,229,506,282