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The gross amount of value received by the entity resulting from the issuance of its convertible subordinated notes.

No definition available.

Name:	cost_GrossProceedsToCompany
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The redemption price, as a percentage of the principal amount, that the Company, upon certain events defined by the terms of the outstanding notes, will be required to make a purchase offer to redeem notes outstanding.

No definition available.

Name:	cost_RedemptionPriceCertainEvents
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The redemption price, as a percentage of the principal amount, that the Company, at its option, may redeem notes outstanding.

No definition available.

Name:	cost_RedemptionPriceCompanyOption
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The rate of return anticipated on a bond if it is held until the maturity date.

No definition available.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Data Type:	num:percentItemType
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The price per share of the conversion feature embedded in the debt instrument.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 20

-Section 50

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The number of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Description of the frequency of periodic payments (monthly, quarterly, annual).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The effective interest rate at the end of the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Contractual interest rate for funds borrowed, under the debt agreement.

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- Details

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The effective interest rate during the reporting period.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

No definition available.

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The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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