Summary of Significant Accounting Policies (Policies)	6 Months Ended
Feb. 13, 2022
Accounting Policies [Abstract]
Basis of Accounting, Policy	Basis of Presentation The condensed consolidated financial statements include the accounts of Costco, its wholly-owned subsidiaries, and subsidiaries in which it has a controlling interest. The Company reports noncontrolling interests in consolidated entities as a component of equity separate from the Company’s equity. All material inter-company transactions among the Company and its consolidated subsidiaries have been eliminated in consolidation. The Company’s net income excludes income attributable to the noncontrolling interest in Taiwan. Unless otherwise noted, references to net income relate to net income attributable to Costco. These unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q for interim financial reporting pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). While these statements reflect all normal recurring adjustments that are, in the opinion of management, necessary for fair presentation of the results of the interim period, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles (U.S. GAAP) for complete financial statements. Therefore, the interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the fiscal year ended August 29, 2021.
Fiscal Period, Policy	Fiscal Year End The Company operates on a 52/53 week fiscal year basis, with the fiscal year ending on the Sunday closest to August 31. Fiscal 2022 is a 52-week year ending on August 28, 2022. References to the second quarter of 2022 and 2021 relate to the 12-week fiscal quarters ended February 13, 2022 and February 14, 2021, respectively. References to the first half of 2022 and 2021 relate to the 24 weeks ended February 13, 2022 and February 14, 2021, respectively.
Use of Estimates, Policy	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates and assumptions take into account historical and forward-looking factors that the Company believes are reasonable. Actual results could differ from those estimates and assumptions.
Property and Equipment, Policy	Property and Equipment, Net The Company capitalizes certain computer software and costs incurred in developing or obtaining software for internal use. The Company recognized a $118 write-off of certain information technology assets, which was recorded in the first quarter of 2022, in selling, general and administrative expenses, in the condensed consolidated statements of income.
Reclassification, Comparability Adjustment	Reclassification Reclassifications were made to our second quarter and first half 2021 condensed consolidated statements of income to conform with current period presentation.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Feb. 13, 2022

Basis of Presentation

The condensed consolidated financial statements include the accounts of Costco, its wholly-owned subsidiaries, and subsidiaries in which it has a controlling interest. The Company reports noncontrolling interests in consolidated entities as a component of equity separate from the Company’s equity. All material inter-company transactions among the Company and its consolidated subsidiaries have been eliminated in consolidation. The Company’s net income excludes income attributable to the noncontrolling interest in Taiwan. Unless otherwise noted, references to net income relate to net income attributable to Costco.

These unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q for interim financial reporting pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). While these statements reflect all normal recurring adjustments that are, in the opinion of management, necessary for fair presentation of the results of the interim period, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles (U.S. GAAP) for complete financial statements. Therefore, the interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the fiscal year ended August 29, 2021.

Fiscal Period, Policy

Fiscal Year End

The Company operates on a 52/53 week fiscal year basis, with the fiscal year ending on the Sunday closest to August 31. Fiscal 2022 is a 52-week year ending on August 28, 2022. References to the second quarter of 2022 and 2021 relate to the 12-week fiscal quarters ended February 13, 2022 and February 14, 2021, respectively. References to the first half of 2022 and 2021 relate to the 24 weeks ended February 13, 2022 and February 14, 2021, respectively.

Use of Estimates, Policy

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates and assumptions take into account historical and forward-looking factors that the Company believes are reasonable. Actual results could differ from those estimates and assumptions.

Property and Equipment, Policy

Property and Equipment, Net

The Company capitalizes certain computer software and costs incurred in developing or obtaining software for internal use. The Company recognized a $118 write-off of certain information technology assets, which was recorded in the first quarter of 2022, in selling, general and administrative expenses, in the condensed consolidated statements of income.

Reclassification, Comparability Adjustment

Reclassification

Reclassifications were made to our second quarter and first half 2021 condensed consolidated statements of income to conform with current period presentation.