Condensed Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 15, 2015	Feb. 16, 2014	Feb. 15, 2015	Feb. 16, 2014
Statement of Comprehensive Income [Abstract]
NET INCOME INCLUDING NONCONTROLLING INTERESTS	$ 607us-gaap_ProfitLoss	$ 473us-gaap_ProfitLoss	$ 1,112us-gaap_ProfitLoss	$ 904us-gaap_ProfitLoss
Foreign-currency translation adjustment and other, net	(410)	(120)	(732)	(36)
Comprehensive income	197	353	380	868
Less: Comprehensive income attributable to noncontrolling interests	8	6	7	15
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	$ 189us-gaap_ComprehensiveIncomeNetOfTax	$ 347us-gaap_ComprehensiveIncomeNetOfTax	$ 373us-gaap_ComprehensiveIncomeNetOfTax	$ 853us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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