Consolidated Statements Of Income (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended									4 Months Ended			12 Months Ended
	May 12, 2013	Feb. 17, 2013		Nov. 25, 2012	May 06, 2012		Feb. 12, 2012	Nov. 20, 2011		Sep. 01, 2013	Sep. 02, 2012		Sep. 01, 2013	Sep. 02, 2012	Aug. 28, 2011
REVENUE
Net sales	$ 23,552	$ 24,343		$ 23,204	$ 21,849		$ 22,508	$ 21,181		$ 31,771	$ 31,524		$ 102,870	$ 97,062	$ 87,048
Membership fees	531	528		511	475		459	447		716	694		2,286	2,075	1,867
Total revenue	24,083	24,871		23,715	22,324		22,967	21,628		32,487	32,218		105,156	99,137	88,915
OPERATING EXPENSES
Merchandise costs	21,038	21,766		20,726	19,543		20,139	18,931		28,418	28,210		91,948	86,823	77,739
Selling, general and administrative	2,313	2,361		2,332	2,152		2,178	2,144	[1]	3,098	3,044		10,104	9,518	8,691
Preopening expenses	10	6		18	6		6	10		17	15		51	37	46
Operating income	722	738		639	623		644	543		954	949		3,053	2,759	2,439
OTHER INCOME (EXPENSE)
Interest expense	(25)	(25)		(13)	(19)		(27)	(27)		(36)	(22)		(99)	(95)	(116)
Interest income and other, net	15	26		20	18		10	37		36	38		97	103	60
INCOME BEFORE INCOME TAXES	712	739		646	622		627	553		954	965		3,051	2,767	2,383
Provision for income taxes	248	185	[2]	225	217		215	225	[3]	332	343		990	1,000	841
Net income including noncontrolling interests	464	554		421	405		412	328		622	622		2,061	1,767	1,542
Net income attributable to noncontrolling interests	(5)	(7)		(5)	(19)		(18)	(8)		(5)	(13)		(22)	(58)	(80)
NET INCOME ATTRIBUTABLE TO COSTCO	$ 459	$ 547		$ 416	$ 386		$ 394	$ 320		$ 617	$ 609		$ 2,039	$ 1,709	$ 1,462
NET INCOME PER COMMON SHARE ATTRIBUTABLE TO COSTCO:
Basic (in dollars per share)	$ 1.05	$ 1.26		$ 0.96	$ 0.89		$ 0.91	$ 0.74		$ 1.41	$ 1.41		$ 4.68	$ 3.94	$ 3.35
Diluted (in dollars per share)	$ 1.04	$ 1.24		$ 0.95	$ 0.88		$ 0.90	$ 0.73		$ 1.40	$ 1.39		$ 4.63	$ 3.89	$ 3.30
Shares used in calculation (000's)
Basic (shares)	436,488	435,975		433,423	433,791		434,535	434,222		436,752	432,437		435,741	433,620	436,119
Diluted (shares)	440,780	439,812		438,643	439,166		439,468	440,615		441,907	438,344		440,512	439,373	443,094
CASH DIVIDENDS DECLARED PER COMMON SHARE	$ 0.31	$ 7.275	[4]	$ 0.275	$ 0	[5]	$ 0.24	$ 0.24		$ 0.31	$ 0.55	[6]	$ 8.17	$ 1.03	$ 0.89

[1] Includes a $17 charge to selling, general and administrative for contributions to an initiative reforming alcohol beverage laws in Washington State.

[2] Includes a $62 tax benefit recorded in the second quarter in connection with the special cash dividend paid to employees through the Company's 401(k) Retirement Plan.

[3] Includes a $24 charge relating to the settlement of an income tax audit in Mexico.

[4] Includes the special cash dividend of $7.00 per share paid in December 2012.

[5] On May 9, 2012, subsequent to the end of the third quarter of 2012, the Board of Directors declared a quarterly cash dividend of $0.275 per share.

[6] The quarterly dividend rate was $0.275 per share.