Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended		8 Months Ended
	May 13, 2018	May 07, 2017	May 13, 2018	May 07, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			$ 11,079	$ 12,332
Comprehensive income:
Net income	$ 762	$ 706	2,126	1,782
Foreign-currency translation adjustment and other, net	(149)	21	(22)	(210)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	609	712	2,067	1,538
Comprehensive income (loss), net of tax, attributable to noncontrolling interest	4	15	37	34
Comprehensive income	613	727	2,104	1,572
Stock-based compensation			434	404
Release of vested restricted stock units (RSUs), including tax effects			(217)	(165)
Repurchase of common stock	(55)	(45)	(233)	(233)
Cash dividends declared and other			(720)	(3,725)
Equity at end of period	12,447	10,185	12,447	10,185
Attributable to Costco
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			10,778	12,079
Comprehensive income:
Net income			2,091	1,760
Foreign-currency translation adjustment and other, net			(24)	(222)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO			2,067	1,538
Stock-based compensation			434	404
Release of vested restricted stock units (RSUs), including tax effects			(217)	(165)
Repurchase of common stock			(233)	(233)
Cash dividends declared and other			(686)	(3,725)
Equity at end of period	12,143	9,898	12,143	9,898
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period			301	253
Comprehensive income:
Net income			35	22
Foreign-currency translation adjustment and other, net			2	12
Comprehensive income (loss), net of tax, attributable to noncontrolling interest			37	34
Cash dividends declared and other			(34)	0
Equity at end of period	$ 304	$ 287	$ 304	$ 287