Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended							4 Months Ended		12 Months Ended
	May 08, 2016	Feb. 14, 2016	Nov. 22, 2015	May 10, 2015	Feb. 15, 2015		Nov. 23, 2014	Aug. 28, 2016	Aug. 30, 2015	Aug. 28, 2016	Aug. 30, 2015	Aug. 31, 2014
REVENUE
Net sales	$ 26,151	$ 27,567	$ 26,627	$ 25,517	$ 26,872		$ 26,284	$ 35,728	$ 34,993	$ 116,073	$ 113,666	$ 110,212
Membership fees	618	603	593	584	582		582	832	785	2,646	2,533	2,428
Total revenue	26,769	28,170	27,220	26,101	27,454		26,866	36,560	35,778	118,719	116,199	112,640
OPERATING EXPENSES
Merchandise costs	23,162	24,469	23,621	22,687	23,897		23,385	31,649	31,096	102,901	101,065	98,458
Selling, general and administrative	2,731	2,835	2,806	2,579	2,671		2,696	3,696	3,499	12,068	11,445	10,899
Preopening expenses	18	10	26	14	9		15	24	27	78	65	63
Operating income	858	856	767	821	877		770	1,191	1,156	3,672	3,624	3,220
OTHER INCOME (EXPENSE)
Interest expense	(30)	(31)	(33)	(31)	(27)		(26)	(39)	(40)	(133)	(124)	(113)
Interest income and other, net	7	16	28	9	20		35	29	40	80	104	90
INCOME BEFORE INCOME TAXES	835	841	762	799	870		779	1,181	1,156	3,619	3,604	3,197
Provision for income taxes	286	286	275	280	263	[1]	274	396	378	1,243	1,195	1,109
Net income including noncontrolling interests	549	555	487	519	607		505	785	778	2,376	2,409	2,088
Net income attributable to noncontrolling interests	(4)	(9)	(7)	(3)	(9)		(9)	(6)	(11)	(26)	(32)	(30)
NET INCOME ATTRIBUTABLE TO COSTCO	$ 545	$ 546	$ 480	$ 516	$ 598		$ 496	$ 779	$ 767	$ 2,350	$ 2,377	$ 2,058
NET INCOME PER COMMON SHARE ATTRIBUTABLE TO COSTCO:
Basic	$ 1.24	$ 1.24	$ 1.10	$ 1.17	$ 1.36		$ 1.13	$ 1.78	$ 1.75	$ 5.36	$ 5.41	$ 4.69
Diluted	$ 1.24	$ 1.24	$ 1.09	$ 1.17	$ 1.35		$ 1.12	$ 1.77	$ 1.73	$ 5.33	$ 5.37	$ 4.65
Shares used in calculation (000's)
Basic (shares)	438,815	439,648	438,342	440,070	440,384		438,760	437,809	438,835	438,585	439,455	438,693
Diluted (shares)	441,066	441,559	441,386	443,132	442,896		442,210	440,868	442,404	441,263	442,716	442,485
CASH DIVIDENDS DECLARED PER COMMON SHARE	$ 0.45	$ 0.40	$ 0.40	$ 0.40	$ 5.355	[2]	$ 0.355	$ 0.45	$ 0.40	$ 1.70	$ 6.51	$ 1.33
Special Dividend [Member]
Quarterly Financial Data [Line Items]
Effective income tax rate reconciliation, deduction, dividends, amount											$ 57
Dividends paid per share											$ 5

[1] Includes a $57 tax benefit recorded in the second quarter in connection with the special cash dividend paid to employees through the Company's 401(k) Retirement Plan.

[2] Includes the special cash dividend of $5.00 per share paid in February 2015.