Condensed Consolidated Statements Of Income (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 15, 2015	Feb. 16, 2014	Feb. 15, 2015	Feb. 16, 2014
Document Period End Date			Feb. 15, 2015
REVENUE
Net sales	$ 26,872us-gaap_SalesRevenueNet	$ 25,756us-gaap_SalesRevenueNet	$ 53,156us-gaap_SalesRevenueNet	$ 50,224us-gaap_SalesRevenueNet
Membership fees	582	550	1,164	1,099
Total revenue	27,454us-gaap_Revenues	26,306us-gaap_Revenues	54,320us-gaap_Revenues	51,323us-gaap_Revenues
OPERATING EXPENSES
Merchandise costs	23,897us-gaap_CostOfGoodsSold	23,043us-gaap_CostOfGoodsSold	47,282us-gaap_CostOfGoodsSold	44,867us-gaap_CostOfGoodsSold
Selling, general and administrative	2,671	2,531	5,367	5,032
Preopening expenses	9us-gaap_PreOpeningCosts	8us-gaap_PreOpeningCosts	24us-gaap_PreOpeningCosts	32us-gaap_PreOpeningCosts
Operating income	877us-gaap_OperatingIncomeLoss	724us-gaap_OperatingIncomeLoss	1,647us-gaap_OperatingIncomeLoss	1,392us-gaap_OperatingIncomeLoss
OTHER INCOME (EXPENSE)
Interest expense	(27)us-gaap_InterestExpense	(26)us-gaap_InterestExpense	(53)us-gaap_InterestExpense	(53)us-gaap_InterestExpense
Interest income and other, net	20us-gaap_InterestAndOtherIncome	30us-gaap_InterestAndOtherIncome	55us-gaap_InterestAndOtherIncome	48us-gaap_InterestAndOtherIncome
INCOME BEFORE INCOME TAXES	870	728	1,649	1,387
Provision for income taxes	263us-gaap_IncomeTaxExpenseBenefit	255us-gaap_IncomeTaxExpenseBenefit	537us-gaap_IncomeTaxExpenseBenefit	483us-gaap_IncomeTaxExpenseBenefit
Net income including noncontrolling interests	607us-gaap_ProfitLoss	473us-gaap_ProfitLoss	1,112us-gaap_ProfitLoss	904us-gaap_ProfitLoss
Net income attributable to noncontrolling interests	(9)	(10)	(18)	(16)
NET INCOME ATTRIBUTABLE TO COSTCO	$ 598us-gaap_NetIncomeLoss	$ 463us-gaap_NetIncomeLoss	$ 1,094us-gaap_NetIncomeLoss	$ 888us-gaap_NetIncomeLoss
NET INCOME PER COMMON SHARE ATTRIBUTABLE TO COSTCO:
Basic (in dollars per share)	$ 1.36us-gaap_EarningsPerShareBasic	$ 1.05us-gaap_EarningsPerShareBasic	$ 2.49us-gaap_EarningsPerShareBasic	$ 2.02us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 1.35us-gaap_EarningsPerShareDiluted	$ 1.05us-gaap_EarningsPerShareDiluted	$ 2.47us-gaap_EarningsPerShareDiluted	$ 2.01us-gaap_EarningsPerShareDiluted
Cash Dividends Declared Per Common Share	$ 5.355	$ 0.31	$ 5.71	$ 0.62
Shares used in calculation (000's)
Basic (shares)	440,384	439,776	439,567	438,868
Diluted (shares)	442,896	442,829	442,522	442,627

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