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Stock-Based Compensation Plans - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified |
6 Months Ended | ||||
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Feb. 15, 2015
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Feb. 09, 2015
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Aug. 31, 2014
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Feb. 04, 2015
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Feb. 05, 2015
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Additional number of shares authorized | 23,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized | ||||
| Special cash dividend shares adjustment ratio | 1.0429cost_SpecialCashDividendSharesAdjustmentRatio | ||||
| Special cash dividend exercise price adjustment ratio | 0.9589cost_SpecialCashDividendExercisePriceAdjustmentRatio | ||||
| Number of stock options outstanding | 410,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | ||||
| Number of RSUs outstanding | 8,956,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber | ||||
| Restricted Stock Units (RSUs) | |||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Additional number of shares authorized | 13,429,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Additional shares available to be granted | 750,000cost_MandatoryProportionalAdjustmentSharesAvailableToGrant / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Number of RSUs outstanding | 9,332,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
9,117,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Number of shares available to be granted as RSUs | 18,242,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Time-based RSUs awards outstanding | 8,786,000cost_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingTimeBased / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Performance-based RSUs awards outstanding | 265,000cost_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingPerformanceBased / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Outstanding performance-based RSUs awards to be granted | 281,000cost_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingPerformanceBasedToBeGranted / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Unrecognized compensation cost | 808us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |
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| Weighted-average recognition period | 1 year 10 months 2 days | ||||
| Closing [Member] | |||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Share price | $ 155.92us-gaap_SharePrice / cost_StockOptionsAxis = cost_ClosingMember |
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| Opening [Member] | |||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Share price | $ 149.50us-gaap_SharePrice / cost_StockOptionsAxis = cost_OpeningMember |
| X | ||||||||||
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- Definition
Mandatory adjustment to shares available to grant on the effective date of a special cash dividend. No definition available.
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- Definition
Number of performance-based compensation awards outstanding at the end of the period. No definition available.
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- Definition
Number of performance-based compensation awards granted to executive officers upon achievement of the specified performance targets as approved by the Company's Board of Directors. No definition available.
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- Definition
The number of time-based compensation restricted stock units outstanding at the end of the period. No definition available.
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- Definition
Represents the exercise price adjustment ratio of the NASDAQ opening price on February 5, 2015, the ex-dividend date, to the closing price on February 4, 2015. No definition available.
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- Definition
Represents the outstanding shares adjustment ratio of the NASDAQ closing price on February 4, 2015, to the NASDAQ opening price on February 5, 2015, the ex-dividend date. No definition available.
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- Definition
Unrecognized cost of unvested share-based compensation awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Number of additional shares authorized for issuance under an established share-based compensation plan. No definition available.
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- Definition
The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Price of a single share of a number of saleable stocks of a company. No definition available.
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- Details
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- Details
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- Details
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