Consolidated Statements of Equity And Comprehensive Income (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Retained Earnings	Total Costco Stockholders' Equity	Noncontrolling Interests
Beginning Balance at Aug. 30, 2009	$ 10,104	$ 2	$ 3,811	$ 110	$ 6,101	$ 10,024	$ 80
Beginning Balance (in shares) at Aug. 30, 2009		435,974,000
Comprehensive Income:
Net income	1,323				1,303	1,303	20
Foreign-currency translation adjustment and other, net	13			12		12	1
Comprehensive income	1,336					1,315	21
Stock-based compensation	190		190			190
Stock options exercised, including tax effects (in shares)		5,576,000
Stock options exercised, including tax effects	243	0	243			243
Release of vested restricted stock units (RSUs), including tax effects (share)		1,885,000
Release of vested restricted stock units (RSUs), including tax effects	(38)	0	(38)			(38)
Conversion of convertible notes, shares		18,000
Conversion of convertible notes	1	0	1			1
Repurchases of common stock, shares	(9,943,000)	(9,943,000)
Repurchases of common stock	(568)	0	(92)		(476)	(568)
Cash dividends declared	(338)				(338)	(338)
Ending Balance at Aug. 29, 2010	10,930	2	4,115	122	6,590	10,829	101
Ending Balance (in shares) at Aug. 29, 2010		433,510,000
Initial consolidation of noncontrolling interest in Costco Mexico	357					0	357
Comprehensive Income:
Net income	1,542				1,462	1,462	80
Foreign-currency translation adjustment and other, net	275			251		251	24
Comprehensive income	1,817					1,713	104
Stock-based compensation	207		207			207
Stock options exercised, including tax effects (in shares)		7,245,000
Stock options exercised, including tax effects	332	0	332			332
Release of vested restricted stock units (RSUs), including tax effects (share)		2,385,000
Release of vested restricted stock units (RSUs), including tax effects	(51)	0	(51)			(51)
Conversion of convertible notes, shares		65,000
Conversion of convertible notes	2	0	2			2
Repurchases of common stock, shares	(8,939,000)	(8,939,000)
Repurchases of common stock	(641)	0	(89)		(552)	(641)
Cash dividends declared	(389)				(389)	(389)
Investment by noncontrolling interest	9						9
Ending Balance at Aug. 28, 2011	12,573	2	4,516	373	7,111	12,002	571
Ending Balance (in shares) at Aug. 28, 2011	434,266,000	434,266,000
Comprehensive Income:
Net income	1,767				1,709	1,709	58
Foreign-currency translation adjustment and other, net	(96)			(62)		(62)	(34)
Comprehensive income	1,671					1,647	24
Stock-based compensation	241		241			241
Stock options exercised, including tax effects (in shares)	2,756,000	2,756,000
Stock options exercised, including tax effects	142	0	142			142
Release of vested restricted stock units (RSUs), including tax effects (share)		2,554,000
Release of vested restricted stock units (RSUs), including tax effects	(76)	0	(76)			(76)
Conversion of convertible notes, shares		46,000
Conversion of convertible notes	2	0	2			2
Repurchases of common stock, shares	(7,272,000)	(7,272,000)
Repurchases of common stock	(617)	0	(77)		(540)	(617)
Cash dividends declared	(446)				(446)	(446)
Distribution to noncontrolling interest	(183)						(183)
Purchase of noncontrolling interest in Costco Mexico	(789)		(379)	(155)		(534)	(255)
Ending Balance at Sep. 02, 2012	$ 12,518	$ 2	$ 4,369	$ 156	$ 7,834	$ 12,361	$ 157
Ending Balance (in shares) at Sep. 02, 2012	432,350,000	432,350,000