Cover
| Cover | 12 Months Ended | |
| Aug. 09, 2023 | Sep. 03, 2023 | |
| Cover [Abstract] | ||
| Amendment Flag | false | |
| Entity Central Index Key | 0000909832 | |
| Document Type | 8-K | |
| Document Period End Date | Aug. 09, 2023 | |
| Entity Registrant Name | COSTCO WHOLESALE CORP /NEW | |
| Entity Incorporation, State or Country Code | WA | |
| Entity File Number | 0-20355 | |
| Entity Tax Identification Number | 91-1223280 | |
| Entity Address, Address Line One | 999 Lake Drive | |
| Entity Address, City or Town | Issaquah | |
| Entity Address, State or Province | WA | |
| Entity Address, Postal Zip Code | 98027 | |
| City Area Code | 425 | |
| Local Phone Number | 313-8100 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Title of 12(b) Security | Common Stock, par value $.005 per share | |
| Trading Symbol | COST | |
| Security Exchange Name | NASDAQ | |
| Entity Emerging Growth Company | false | |
| Current Fiscal Year End Date | --09-03 |