Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 17, 2013	Feb. 12, 2012	Feb. 17, 2013	Feb. 12, 2012
Equity And Comprehensive Income [Line Items]
Beginning Balance			$ 12,518	$ 12,573
Comprehensive income:
Net income	554	412	975	740
Foreign-currency translation adjustment and other, net	(65)	132	(43)	(77)
Comprehensive income	489	544	932	663
Stock-based compensation	66	58	159	134
Stock options exercised, including tax effects			51	49
Release of vested restricted stock units (RSUs), including tax effects			(83)	(74)
Conversion of convertible notes			29	1
Repurchases of common stock		(145)	(34)	(318)
Cash dividends declared			(3,289)	(209)
Ending Balance	10,283	12,819	10,283	12,819
Attributable to Costco
Equity And Comprehensive Income [Line Items]
Beginning Balance			12,361	12,002
Comprehensive income:
Net income			963	714
Foreign-currency translation adjustment and other, net			(45)	(67)
Comprehensive income			918	647
Stock-based compensation			159	134
Stock options exercised, including tax effects			51	49
Release of vested restricted stock units (RSUs), including tax effects			(83)	(74)
Conversion of convertible notes			29	1
Repurchases of common stock			(34)	(318)
Cash dividends declared			(3,289)	(209)
Ending Balance	10,112	12,232	10,112	12,232
Noncontrolling Interest
Equity And Comprehensive Income [Line Items]
Beginning Balance			157	571
Comprehensive income:
Net income			12	26
Foreign-currency translation adjustment and other, net			2	(10)
Comprehensive income			14	16
Stock-based compensation			0	0
Stock options exercised, including tax effects			0	0
Release of vested restricted stock units (RSUs), including tax effects			0	0
Conversion of convertible notes			0	0
Repurchases of common stock			0	0
Cash dividends declared			0	0
Ending Balance	$ 171	$ 587	$ 171	$ 587