Commitments and Contingencies	6 Months Ended
Feb. 18, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Legal Proceedings The Company is involved in a number of claims, proceedings and litigation arising from its business and property ownership. In accordance with applicable accounting guidance, the Company establishes an accrual for legal proceedings if and when those matters reach a stage where they present loss contingencies that are both probable and reasonably estimable. There may be exposure to loss in excess of any amounts accrued. The Company monitors those matters for developments that would affect the likelihood of a loss (taking into account where applicable indemnification arrangements concerning suppliers and insurers) and the accrued amount, if any, thereof, and adjusts the amount as appropriate. As of the date of this Report, the Company has recorded an immaterial accrual with respect to one matter described below, in addition to other immaterial accruals for matters not described below. If the loss contingency at issue is not both probable and reasonably estimable, the Company does not establish an accrual, but will continue to monitor the matter for developments that will make the loss contingency both probable and reasonably estimable. In each case, there is a reasonable possibility that a loss may be incurred, including a loss in excess of the applicable accrual. For matters where no accrual has been recorded, the possible loss or range of loss (including any loss in excess of the accrual) cannot, in the Company's view, be reasonably estimated because, among other things: (i) the remedies or penalties sought are indeterminate or unspecified; (ii) the legal and/or factual theories are not well developed; and/or (iii) the matters involve complex or novel legal theories or a large number of parties. The Company is a defendant in a class action alleging violation of California Wage Order 7-2001 by failing to provide seating to member service assistants who act as greeters and exit attendants in the Company’s California warehouses. Canela v. Costco Wholesale Corp., et al. (Case No. 5:13-cv-03598, N.D. Cal. filed July 1, 2013). The complaint seeks relief under the California Labor Code, including civil penalties and attorneys’ fees. The Company has filed an answer denying the material allegations of the complaint. On November 23, 2016, the Company’s Canadian subsidiary received from the Ontario Ministry of Health and Long Term Care a request for an inspection and information concerning compliance with the anti-rebate provisions in the Ontario Drug Benefit Act and the Drug Interchangeability and Dispensing Fee Act. The Company is seeking to cooperate with the request. In November 2016 and September 2017, the Company received notices of violation from the Connecticut Department of Energy and Environmental Protection regarding hazardous waste practices at its Connecticut warehouses, primarily concerning unsalable pharmaceuticals. The Company is seeking to cooperate concerning the resolution of these notices. The Company does not believe that any pending claim, proceeding or litigation, either alone or in the aggregate, will have a material adverse effect on the Company’s financial position, results of operations or cash flows; however, it is possible that an unfavorable outcome of some or all of the matters, however unlikely, could result in a charge that might be material to the results of an individual fiscal quarter.

Legal Proceedings

The Company is involved in a number of claims, proceedings and litigation arising from its business and property ownership. In accordance with applicable accounting guidance, the Company establishes an accrual for legal proceedings if and when those matters reach a stage where they present loss contingencies that are both probable and reasonably estimable. There may be exposure to loss in excess of any amounts accrued. The Company monitors those matters for developments that would affect the likelihood of a loss (taking into account where applicable indemnification arrangements concerning suppliers and insurers) and the accrued amount, if any, thereof, and adjusts the amount as appropriate. As of the date of this Report, the Company has recorded an immaterial accrual with respect to one matter described below, in addition to other immaterial accruals for matters not described below. If the loss contingency at issue is not both probable and reasonably estimable, the Company does not establish an accrual, but will continue to monitor the matter for developments that will make the loss contingency both probable and reasonably estimable. In each case, there is a reasonable possibility that a loss may be incurred, including a loss in excess of the applicable accrual. For matters where no accrual has been recorded, the possible loss or range of loss (including any loss in excess of the accrual) cannot, in the Company's view, be reasonably estimated because, among other things: (i) the remedies or penalties sought are indeterminate or unspecified; (ii) the legal and/or factual theories are not well developed; and/or (iii) the matters involve complex or novel legal theories or a large number of parties.

The Company is a defendant in a class action alleging violation of California Wage Order 7-2001 by failing to provide seating to member service assistants who act as greeters and exit attendants in the Company’s California warehouses. Canela v. Costco Wholesale Corp., et al. (Case No. 5:13-cv-03598, N.D. Cal. filed July 1, 2013). The complaint seeks relief under the California Labor Code, including civil penalties and attorneys’ fees. The Company has filed an answer denying the material allegations of the complaint.

On November 23, 2016, the Company’s Canadian subsidiary received from the Ontario Ministry of Health and Long Term Care a request for an inspection and information concerning compliance with the anti-rebate provisions in the Ontario Drug Benefit Act and the Drug Interchangeability and Dispensing Fee Act. The Company is seeking to cooperate with the request.

In November 2016 and September 2017, the Company received notices of violation from the Connecticut Department of Energy and Environmental Protection regarding hazardous waste practices at its Connecticut warehouses, primarily concerning unsalable pharmaceuticals. The Company is seeking to cooperate concerning the resolution of these notices.

The Company does not believe that any pending claim, proceeding or litigation, either alone or in the aggregate, will have a material adverse effect on the Company’s financial position, results of operations or cash flows; however, it is possible that an unfavorable outcome of some or all of the matters, however unlikely, could result in a charge that might be material to the results of an individual fiscal quarter.