Summary of Significant Accounting Policies (Policies)	3 Months Ended
May 02, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation. The accompanying unaudited interim condensed consolidated financial statements have been prepared from the records of Ross Stores, Inc. and subsidiaries (the “Company”) without audit and, in the opinion of management, include all adjustments (consisting of only normal, recurring adjustments) necessary to present fairly the Company’s financial position as of May 2, 2020 and May 4, 2019, the results of operations, comprehensive (loss) income, stockholders' equity, and cash flows for the three month periods ended May 2, 2020 and May 4, 2019. The Condensed Consolidated Balance Sheet as of February 1, 2020, presented herein, has been derived from the Company’s audited consolidated financial statements for the fiscal year then ended. Certain information and disclosures normally included in the notes to annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") have been condensed or omitted for purposes of these interim condensed consolidated financial statements. The interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including notes thereto, contained in the Company’s Annual Report on Form 10-K for the year ended February 1, 2020. The results of operations, comprehensive (loss) income, stockholders' equity, and cash flows for the three month periods ended May 2, 2020 and May 4, 2019 presented herein are not necessarily indicative of the results to be expected for the full fiscal year. Use of accounting estimates. The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets, liabilities, and disclosures of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. The Company’s significant accounting estimates include valuation reserves for inventory (including shortage), packaway inventory costs, useful lives of fixed assets, insurance reserves, reserves for uncertain tax positions, estimates for provisions of the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"), and legal claims. Given the global economic climate and additional, or unforeseen effects, from the COVID-19 pandemic, these estimates are more challenging, and actual results could differ materially from the Company's estimates.
Use of accounting estimates	Use of accounting estimates. The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets, liabilities, and disclosures of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. The Company’s significant accounting estimates include valuation reserves for inventory (including shortage), packaway inventory costs, useful lives of fixed assets, insurance reserves, reserves for uncertain tax positions, estimates for provisions of the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"), and legal claims. Given the global economic climate and additional, or unforeseen effects, from the COVID-19 pandemic, these estimates are more challenging, and actual results could differ materially from the Company's estimates.
Cash, restricted cash, and restricted investments	Cash, restricted cash, and restricted investments. Restricted cash, cash equivalents, and investments serve as collateral for certain insurance obligations of the Company. These restricted funds are invested in bank deposits, money market mutual funds, U.S. Government and agency securities, and corporate securities and cannot be withdrawn from the Company’s account without the prior written consent of the secured parties. The classification between current and long-term is based on the timing of expected payments of the insurance obligations.
Property and equipment	Property and equipment. As of May 2, 2020 and May 4, 2019, the Company had $34.5 million and $14.8 million, respectively, of property and equipment purchased but not yet paid. These purchases are included in Property and Equipment, Accounts payable, and Accrued expenses and other in the accompanying Condensed Consolidated Balance Sheets.
Recently adopted accounting standards and Recently issued accounting standards	Recently adopted accounting standards. In December 2019, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2019-12, Simplifying the Accounting for Income Taxes (Accounting Standards Codification "ASC" 740). ASU 2019-12 eliminates certain exceptions in ASC 740 related to the methodology for calculating income taxes in an interim period. It also clarifies and simplifies other aspects of the accounting for income taxes. The amendments in ASU 2019-12 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted, including adoption in any interim period. The Company adopted ASU 2019-12 on a prospective basis in the first quarter of fiscal 2020. The most significant impact to the Company is the removal of a limit on the tax benefit recognized on pre-tax losses in interim periods. The adoption of this standard did not have a material impact on the Company's condensed consolidated financial statements for the first quarter of fiscal 2020 and is not expected to have a material impact on the Company's fiscal 2020 results. Recently issued accounting standards. The Company considers the applicability and impact of all ASUs issued by the FASB. For the three month period ended May 2, 2020, the ASUs issued by the FASB were assessed and determined to be either not applicable or are expected to have minimal impact on the Company's condensed consolidated financial results.
Fair value measurement	Fair Value Measurements The carrying value of cash and cash equivalents, short- and long-term investments, restricted cash and cash equivalents, restricted investments, accounts receivable, other long-term assets, accounts payable, and other long-term liabilities approximates their estimated fair value. Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy which prioritizes the inputs used in measuring fair value. The inputs used to measure fair value include: Level 1, observable inputs such as quoted prices in active markets; Level 2, inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, unobservable inputs in which little or no market data exists. This fair value hierarchy requires the Company to develop its own assumptions and maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Corporate, U.S. government and agency, and mortgage-backed securities are classified within Level 1 or Level 2 because these securities are valued using quoted market prices or alternative pricing sources and models utilizing market observable inputs.
Earnings per share	(Loss) Earnings Per ShareThe Company computes and reports both basic (loss) earnings per share ("EPS") and diluted EPS. Basic EPS is computed by dividing net (loss) earnings by the weighted-average number of common shares outstanding for the period. Diluted EPS is computed by dividing net (loss) earnings by the sum of the weighted-average number of common shares and dilutive common stock equivalents outstanding during the period, except in cases where the effect of the common stock equivalents would be antidilutive. Diluted EPS reflects the total potential dilution that could occur from outstanding equity plan awards and unvested shares of both performance and non-performance based awards of restricted stock. For periods of net loss, basic and diluted EPS are the same as the effect of the assumed vesting of restricted stock units is anti-dilutive.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

May 02, 2020

Basis of presentation. The accompanying unaudited interim condensed consolidated financial statements have been prepared from the records of Ross Stores, Inc. and subsidiaries (the “Company”) without audit and, in the opinion of management, include all adjustments (consisting of only normal, recurring adjustments) necessary to present fairly the Company’s financial position as of May 2, 2020 and May 4, 2019, the results of operations, comprehensive (loss) income, stockholders' equity, and cash flows for the three month periods ended May 2, 2020 and May 4, 2019. The Condensed Consolidated Balance Sheet as of February 1, 2020, presented herein, has been derived from the Company’s audited consolidated financial statements for the fiscal year then ended.

Certain information and disclosures normally included in the notes to annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") have been condensed or omitted for purposes of these interim condensed consolidated financial statements. The interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including notes thereto, contained in the Company’s Annual Report on Form 10-K for the year ended February 1, 2020.

The results of operations, comprehensive (loss) income, stockholders' equity, and cash flows for the three month periods ended May 2, 2020 and May 4, 2019 presented herein are not necessarily indicative of the results to be expected for the full fiscal year.

Use of accounting estimates. The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets, liabilities, and disclosures of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. The Company’s significant accounting estimates include valuation reserves for inventory (including shortage), packaway inventory costs, useful lives of fixed assets, insurance reserves, reserves for uncertain tax positions, estimates for provisions of the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"), and legal claims. Given the global economic climate and additional, or unforeseen effects, from the COVID-19 pandemic, these estimates are more challenging, and actual results could differ materially from the Company's estimates.

Use of accounting estimates

Cash, restricted cash, and restricted investments

Cash, restricted cash, and restricted investments. Restricted cash, cash equivalents, and investments serve as collateral for certain insurance obligations of the Company. These restricted funds are invested in bank deposits, money market mutual funds, U.S. Government and agency securities, and corporate securities and cannot be withdrawn from the Company’s account without the prior written consent of the secured parties. The classification between current and long-term is based on the timing of expected payments of the insurance obligations.

Property and equipment

Property and equipment. As of May 2, 2020 and May 4, 2019, the Company had $34.5 million and $14.8 million, respectively, of property and equipment purchased but not yet paid. These purchases are included in Property and Equipment, Accounts payable, and Accrued expenses and other in the accompanying Condensed Consolidated Balance Sheets.

Recently adopted accounting standards and Recently issued accounting standards

Recently adopted accounting standards. In December 2019, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2019-12, Simplifying the Accounting for Income Taxes (Accounting Standards Codification "ASC" 740). ASU 2019-12 eliminates certain exceptions in ASC 740 related to the methodology for calculating income taxes in an interim period. It also clarifies and simplifies other aspects of the accounting for income taxes. The amendments in ASU 2019-12 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted, including adoption in any interim period. The Company adopted ASU 2019-12 on a prospective basis in the first quarter of fiscal 2020. The most significant impact to the Company is the removal of a limit on the tax benefit recognized on pre-tax losses in interim periods. The adoption of this standard did not have a material impact on the Company's condensed consolidated financial statements for the first quarter of fiscal 2020 and is not expected to have a material impact on the Company's fiscal 2020 results.

Recently issued accounting standards. The Company considers the applicability and impact of all ASUs issued by the FASB. For the three month period ended May 2, 2020, the ASUs issued by the FASB were assessed and determined to be either not applicable or are expected to have minimal impact on the Company's condensed consolidated financial results.

Fair value measurement

Fair Value Measurements

The carrying value of cash and cash equivalents, short- and long-term investments, restricted cash and cash equivalents, restricted investments, accounts receivable, other long-term assets, accounts payable, and other long-term liabilities approximates their estimated fair value.

Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy which prioritizes the inputs used in measuring fair value. The inputs used to measure fair value include: Level 1, observable inputs such as quoted prices in active markets; Level 2, inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, unobservable inputs in which little or no market data exists. This fair value hierarchy requires the Company to develop its own assumptions and maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Corporate, U.S. government and agency, and mortgage-backed securities are classified within Level 1 or Level 2 because these securities are valued using quoted market prices or alternative pricing sources and models utilizing market observable inputs.

Earnings per share

(Loss) Earnings Per ShareThe Company computes and reports both basic (loss) earnings per share ("EPS") and diluted EPS. Basic EPS is computed by dividing net (loss) earnings by the weighted-average number of common shares outstanding for the period. Diluted EPS is computed by dividing net (loss) earnings by the sum of the weighted-average number of common shares and dilutive common stock equivalents outstanding during the period, except in cases where the effect of the common stock equivalents would be antidilutive. Diluted EPS reflects the total potential dilution that could occur from outstanding equity plan awards and unvested shares of both performance and non-performance based awards of restricted stock. For periods of net loss, basic and diluted EPS are the same as the effect of the assumed vesting of restricted stock units is anti-dilutive.