Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 15, 2015	Feb. 16, 2014	Feb. 15, 2015	Feb. 16, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			$ 12,515	$ 11,012
Comprehensive income:
Net income	607	473	1,112	904
Foreign-currency translation adjustment and other, net	(410)	(120)	(732)	(36)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	189	347	373	853
Comprehensive income	197	353	380	868
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	8	6	7	15
Stock-based compensation			236	185
Stock options exercised, including tax effects			39	18
Release of vested restricted stock units (RSUs), including tax effects			(121)	(101)
Repurchases of common stock	(92)		(110)
Cash dividends declared			(2,514)	(273)
Equity at end of period	10,425	11,709	10,425	11,709
Attributable to Costco
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			12,303	10,833
Comprehensive income:
Net income			1,094	888
Foreign-currency translation adjustment and other, net			(721)	(35)
Stock-based compensation			236	185
Stock options exercised, including tax effects			39	18
Release of vested restricted stock units (RSUs), including tax effects			(121)	(101)
Repurchases of common stock			(110)
Cash dividends declared			(2,514)	(273)
Equity at end of period	10,206	11,515	10,206	11,515
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			212	179
Comprehensive income:
Net income			18	16
Foreign-currency translation adjustment and other, net			(11)	(1)
Equity at end of period	$ 219	$ 194	$ 219	$ 194