Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 26, 2017	Nov. 20, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	$ 11,079	$ 12,332
Comprehensive income:
Net income	651	555
Foreign-currency translation adjustment and other, net	(23)	(345)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	617	205
Comprehensive income (loss), net of tax, attributable to noncontrolling interest	11	5
Comprehensive income	628	210
Stock-based compensation	235	211
Release of vested restricted stock units (RSUs), including tax effects	216	(162)
Stock Repurchased and Retired During Period, Value	(119)	(122)
Cash dividends declared and other	(251)	(238)
Equity at end of period	11,356	12,231
Attributable to Costco
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	10,778	12,079
Comprehensive income:
Net income	640	545
Foreign-currency translation adjustment and other, net	(23)	(340)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	617	205
Stock-based compensation	235	211
Release of vested restricted stock units (RSUs), including tax effects	216	(162)
Stock Repurchased and Retired During Period, Value	(119)	(122)
Cash dividends declared and other	(217)	(238)
Equity at end of period	11,078	11,973
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	301	253
Comprehensive income:
Net income	11	10
Foreign-currency translation adjustment and other, net	0	(5)
Comprehensive income (loss), net of tax, attributable to noncontrolling interest	11	5
Cash dividends declared and other	(34)	0
Equity at end of period	$ 278	$ 258