Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Nov. 20, 2011	Nov. 21, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income including noncontrolling interests	$ 328	$ 332
Adjustments to reconcile net income including noncontrolling interests to net cash provided by operating activities:
Depreciation and amortization	205	191
Stock-based compensation	76	57
Excess tax benefits on stock-based awards	(36)	(17)
Other non-cash operating activities, net	8	5
Deferred income tax expense	(14)	(5)
Changes in operating assets and liabilities:
Increase in merchandise inventories	(1,062)	(912)
Increase in accounts payable	991	961
Other operating assets and liabilities, net	168	108
Net cash provided by operating activities	664	720
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of short-term investments	(498)	(719)
Maturities of short-term investments	392	479
Sales of investments	95	237
Additions to property and equipment	(343)	(306)
Proceeds from the sale of property and equipment	7	7
Increase resulting from initial consolidation of Costco Mexico	0	165
Other investing activities, net	(5)	0
Net cash used in investing activities	(352)	(137)
CASH FLOWS FROM FINANCING ACTIVITIES
Change in bank checks outstanding	160	73
Repayments of short-term borrowings	(83)	(10)
Proceeds from short-term borrowings	117	8
Proceeds from long-term debt issuance	78	0
Proceeds from exercise of stock options	25	112
Minimum tax withholdings on stock-based awards	(104)	(52)
Excess tax benefits on stock-based awards	36	17
Repurchases of common stock	(163)	(145)
Cash dividend payments	0	(89)
Other financing activities, net	1	(1)
Net cash provided by (used in) financing activities	67	(87)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(69)	29
Net increase in cash and cash equivalents	310	525
CASH AND CASH EQUIVALENTS BEGINNING OF YEAR	4,009	3,214
CASH AND CASH EQUIVALENTS END OF PERIOD	4,319	3,739
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Interest (reduced by $2 and $3 interest capitalized in the first fiscal quarters of 2012 and 2011, respectively)	56	54
Income taxes	148	82
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Decrease in accrued property and equipment	(43)	(35)
Cash dividend declared, but not yet paid	105	0
Unsettled repurchases of common stock	$ 10	$ 5