Changes in Equity Attributes to Costco and the Noncontrolling Interests of Consolidated Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 20, 2016	Nov. 22, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	$ 12,332	$ 10,843
Comprehensive income:
Net income	555	487
Foreign-currency translation adjustment and other, net	(345)	15
COMPREHENSIVE INCOME ATTRIBUTABLE TO COSTCO	205	496
Comprehensive income (loss), net of tax, attributable to noncontrolling interest	5	6
Comprehensive income	210	502
Stock-based compensation	211	186
Release of vested restricted stock units (RSUs), including tax effects	(162)	(145)
Repurchases of common stock	(122)	(130)
Cash dividends declared	(238)	(176)
Equity at end of period	12,231	11,080
Attributable to Costco
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	12,079	10,617
Comprehensive income:
Net income	545	480
Foreign-currency translation adjustment and other, net	(340)	16
Stock-based compensation	211	186
Release of vested restricted stock units (RSUs), including tax effects	(162)	(145)
Repurchases of common stock	(122)	(130)
Cash dividends declared	(238)	(176)
Equity at end of period	11,973	10,848
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity at beginning of period	253	226
Comprehensive income:
Net income	10	7
Foreign-currency translation adjustment and other, net	(5)	(1)
Equity at end of period	$ 258	$ 232