Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended		8 Months Ended
	May 07, 2017	May 08, 2016	May 07, 2017	May 08, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			$ 12,332	$ 10,843
Comprehensive income:
Net income	$ 706	$ 549	1,782	1,591
Foreign-currency translation adjustment and other, net	21	224	(210)	(5)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	712	763	1,538	1,566
Comprehensive income (loss), net of tax, attributable to noncontrolling interest	15	10	34	20
Comprehensive income	727	773	1,572	1,586
Stock-based compensation			404	362
Release of vested restricted stock units (RSUs), including tax effects			(165)	(145)
Repurchases of common stock	(45)	(136)	(233)	(346)
Cash dividends declared			(3,725)	(549)
Distribution to noncontrolling interest				(3)
Equity at end of period	10,185	11,748	10,185	11,748
Attributable to Costco
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			12,079	10,617
Comprehensive income:
Net income			1,760	1,571
Foreign-currency translation adjustment and other, net			(222)	(5)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO			1,538	1,566
Stock-based compensation			404	362
Release of vested restricted stock units (RSUs), including tax effects			(165)	(145)
Repurchases of common stock			(233)	(346)
Cash dividends declared			(3,725)	(549)
Equity at end of period	9,898	11,505	9,898	11,505
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			253	226
Comprehensive income:
Net income			22	20
Foreign-currency translation adjustment and other, net			12	0
Comprehensive income (loss), net of tax, attributable to noncontrolling interest			34	20
Distribution to noncontrolling interest				(3)
Equity at end of period	$ 287	$ 243	$ 287	$ 243