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Equity (Tables) | 6 Months Ended
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Feb. 16, 2020
Equity [Abstract] |
Stock Repurchased During Period | Stock repurchase activity during the second quarter and first half of 2020 and 2019 is summarized below:
| Shares Repurchased (000s) |  | Average Price per Share |  | Total Cost
Second quarter of 2020 | 162 |  |  | $ | 301.50 |  |  | $ | 49 |
First half of 2020 | 262 |  |  | $ | 299.40 |  |  | $ | 79 |
Second quarter of 2019 | 561 |  |  | $ | 208.72 |  |  | $ | 117 |
First half of 2019 | 711 |  |  | $ | 213.08 |  |  | $ | 151 |

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

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