Net Income per Common and Common Equivalent Share - Schedule of Earnings per Share Effect on Net Income and Weighted Averegae Number of Dilutive Potential Common Stock (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended						4 Months Ended		12 Months Ended
	May 10, 2020	Feb. 16, 2020	Nov. 24, 2019	May 12, 2019	Feb. 17, 2019	Nov. 25, 2018	Aug. 30, 2020	Sep. 01, 2019	Aug. 30, 2020	Sep. 01, 2019	Sep. 02, 2018
Earnings Per Share [Abstract]
NET INCOME ATTRIBUTABLE TO COSTCO	$ 838	$ 931	$ 844	$ 906	$ 889	$ 767	$ 1,389	$ 1,097	$ 4,002	$ 3,659	$ 3,134
Weighted average number of common shares used in basic net income per common share	442,322	442,021	441,818	439,859	440,284	439,157	442,843	439,727	442,297	439,755	438,515
RSUs and other									1,604	3,168	3,319
Weighted average number of common shares and dilutive potential of common stock used in diluted net income per share	443,855	443,727	443,680	442,642	442,337	442,749	444,231	443,400	443,901	442,923	441,834