Income Taxes	3 Months Ended
Nov. 20, 2011
Income Taxes [Abstract]
Income Taxes	Note 7—Income Taxes The Company's estimated annual effective tax rate, before reporting the net impact of discrete items, was 35.5% at November 20, 2011, for the fiscal year ending September 2, 2012. The estimated annual effective tax rate was 35.9% at November 21, 2010, for the prior fiscal year ended August 28, 2011. The Company's reported effective tax rates for the quarters ended November 20, 2011 and November 21, 2010 were 40.8% and 34.2%, respectively, in the accompanying condensed consolidated statements of income, which includes the net impact of discrete items. The Company's consolidated provision for income taxes for the quarter ended November 20, 2011, was adversely impacted by a net discrete tax expense of $29 relating primarily to two items: the adverse impact of an audit of Costco Mexico by the Mexican tax authority and the tax effects of nondeductible expenses for the Company's contribution to the Yes on 1183 Coalition in support of an initiative reforming alcohol beverage laws in Washington State. The net discrete benefit for the quarter ended November 21, 2010, was primarily attributable to the resolution of an uncertain tax position, which resulted in a tax refund received by Costco Mexico. The Company is currently evaluating options for seeking a refund of some or all of the taxes paid or payable to the Mexican tax authority relating to the tax audit. However, the Company's ability to prevail in obtaining a refund of the amounts paid or payable to the Mexican tax authority is subject to significant uncertainty.

Income Taxes

3 Months Ended

Nov. 20, 2011

Note 7—Income Taxes

The Company's estimated annual effective tax rate, before reporting the net impact of discrete items, was 35.5% at November 20, 2011, for the fiscal year ending September 2, 2012. The estimated annual effective tax rate was 35.9% at November 21, 2010, for the prior fiscal year ended August 28, 2011. The Company's reported effective tax rates for the quarters ended November 20, 2011 and November 21, 2010 were 40.8% and 34.2%, respectively, in the accompanying condensed consolidated statements of income, which includes the net impact of discrete items. The Company's consolidated provision for income taxes for the quarter ended November 20, 2011, was adversely impacted by a net discrete tax expense of $29 relating primarily to two items: the adverse impact of an audit of Costco Mexico by the Mexican tax authority and the tax effects of nondeductible expenses for the Company's contribution to the Yes on 1183 Coalition in support of an initiative reforming alcohol beverage laws in Washington State. The net discrete benefit for the quarter ended November 21, 2010, was primarily attributable to the resolution of an uncertain tax position, which resulted in a tax refund received by Costco Mexico.

The Company is currently evaluating options for seeking a refund of some or all of the taxes paid or payable to the Mexican tax authority relating to the tax audit. However, the Company's ability to prevail in obtaining a refund of the amounts paid or payable to the Mexican tax authority is subject to significant uncertainty.