XML 33 R23.htm IDEA: XBRL DOCUMENT
v3.20.4

Equity (Tables) | 3 Months Ended
--- | ---
Nov. 22, 2020
Equity [Abstract] |
Stock Repurchased During Period | Stock repurchase activity during the first quarter of 2021 and 2020 is summarized below:
| Shares Repurchased (000s) |  | Average Price per Share |  | Total Cost
First quarter of 2021 | 213 |  |  | $ | 359.45 |  |  | $ | 77 |
First quarter of 2020 | 100 |  |  | $ | 295.97 |  |  | $ | 30 |

X
- Definition Schedule of Common Stock Repurchased And Average Price Paid Per Share [Table Text Block] + References No definition available. + Details
Name: | cost_ScheduleOfCommonStockRepurchasedAndAveragePricePaidPerShareTableTextBlock
Namespace Prefix: | cost_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_EquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration