Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 02, 2012	Aug. 28, 2011	Aug. 29, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income including noncontrolling interests	$ 1,767	$ 1,542	$ 1,323
Adjustments to reconcile net income including noncontrolling interests to net cash provided by operating activities:
Depreciation and amortization	908	855	795
Stock-based compensation	241	207	190
Excess tax benefits on stock-based awards	(64)	(45)	(10)
Other non-cash operating activities, net	28	23	(40)
Deferred income taxes	(3)	84	7
Changes in operating assets and liabilities, net of the initial consolidation of Costco Mexico at the beginning of fiscal 2011:
Increase in merchandise inventories	(490)	(642)	(213)
Increase in accounts payable	338	804	445
Other operating assets and liabilities, net	332	370	283
Net cash provided by operating activities	3,057	3,198	2,780
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of short-term investments	(2,048)	(3,276)	(2,693)
Maturities of short-term investments	1,821	2,614	1,428
Sales of investments	482	602	309
Additions to property and equipment	(1,480)	(1,290)	(1,055)
Proceeds from the sale of property and equipment	11	16	4
Increase resulting from initial consolidation of Costco Mexico	0	165	0
Other investing activities, net	(22)	(11)	(8)
Net cash used in investing activities	(1,236)	(1,180)	(2,015)
CASH FLOWS FROM FINANCING ACTIVITIES
Change in bank checks outstanding	457	(514)	5
Repayments of short-term borrowings	(114)	(105)	(73)
Proceeds from short-term borrowings	114	79	81
Proceeds from issuance of long-term debt	130	0	0
Repayments of long-term debt	(900)	0	(84)
Investment by (distribution to) noncontrolling interests	(161)	9	0
Proceeds from exercise of stock options	109	285	235
Minimum tax withholdings on stock-based awards	(107)	(61)	(42)
Excess tax benefits on stock-based awards	64	45	10
Repurchases of common stock	(632)	(624)	(551)
Cash dividend payments	(446)	(389)	(338)
Purchase of noncontrolling interest in Costco Mexico	(789)	0	0
Other financing activities, net	(6)	(2)	38
Net cash used in financing activities	(2,281)	(1,277)	(719)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(21)	54	11
Net increase (decrease) in cash and cash equivalents	(481)	795	57
CASH AND CASH EQUIVALENTS BEGINNING OF YEAR	4,009	3,214	3,157
CASH AND CASH EQUIVALENTS END OF YEAR	3,528	4,009	3,214
Cash paid during the year for:
Interest (reduced by $10, $9, and $11 interest capitalized in 2012, 2011, and 2010, respectively)	112	111	110
Income taxes	956	742	637
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
(Decrease)/increase in accrued property and equipment	(29)	(10)	24
Property acquired under capital leases	18	0	90
Unsettled repurchases of common stock	2	17	17
Distribution declared but not paid to noncontrolling interest	$ 22	$ 0	$ 0