Organization and principal accounting policies (Policies)	9 Months Ended
	Oct. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of preparation	Basis of preparation These condensed consolidated financial statements included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. In the opinion of management, the accompanying condensed consolidated financial statements reflect all adjustments, which are of a normal recurring nature, necessary for a fair presentation of the results for the interim periods. It is suggested that these condensed consolidated financial statements be read in conjunction with the consolidated financial statements and notes included in Signet’s Annual Report on Form 10-K for the year-ended January 31, 2015
Use of estimates	Use of estimates The preparation of these condensed consolidated financial statements, in conformity with US GAAP and SEC regulations for interim reporting, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are primarily made in relation to the valuation of accounts receivables, inventories, deferred revenue, derivatives, employee benefits, income taxes, contingencies, asset impairments, depreciation and amortization of long-lived assets as well as accounting for business combinations.
Foreign currency transactions	Foreign currency translation The financial position and operating results of certain foreign operations, including the UK Jewelry division and the Canadian operations of the Zale Jewelry segment, are consolidated using the local currency as the functional currency. Assets and liabilities are translated at the rates of exchange on the balance sheet date, and revenues and expenses are translated at the monthly average rates of exchange during the period. Resulting translation gains or losses are included in the accompanying condensed consolidated statements of equity as a component of accumulated other comprehensive income (loss) (“AOCI”). Gains or losses resulting from foreign currency transactions are included within the condensed consolidated statements of operations, whereas translation adjustments and gains or losses related to intercompany loans of a long-term investment nature are recognized as a component of AOCI.
Revenue recognition	Revenue recognition Extended service plans and lifetime warranty agreements The Company recognizes revenue related to lifetime warranty sales in proportion to when the expected costs will be incurred. The deferral period for lifetime warranty sales in each division is determined from patterns of claims costs, including estimates of future claims costs expected to be incurred. Management reviews the trends in claims to assess whether changes are required to the revenue and cost recognition rates utilized. A significant change in estimates related to the time period or pattern in which warranty-related costs are expected to be incurred could materially impact revenues. All direct costs associated with the sale of these plans are deferred and amortized in proportion to the revenue recognized and disclosed as either other current assets or other assets. The Sterling Jewelers division sells extended service plans, subject to certain conditions, to perform repair work over the life of the product. Revenue from the sale of these lifetime extended service plans is recognized consistent with the estimated pattern of claim costs expected to be incurred by the Company in connection with performing under the extended service plan obligations. Based on an evaluation of historical claims data, management currently estimates that substantially all claims will be incurred within 17 years of the sale of the warranty contract. In the second quarter of Fiscal 2016, an operational change related to the Sterling Jewelers division's extended service plans associated with ring sizing was made to further align Zale and Sterling ESP policies. As a result, revenue from the sale of these lifetime extended service plans in the Sterling Jewelers division is deferred and recognized over 17 years for all plans, with approximately 57% of revenue recognized within the first two years for plans sold on or after May 2, 2015 and 42% of revenue recognized within the first two years for plans sold prior to May 2, 2015 (January 31, 2015: 45%; November 1, 2014: 45%). The Zale division also sells extended service plans. Zale Jewelry customers are offered lifetime warranties on certain products that cover sizing and breakage with an option to purchase theft protection for a two-year period. Revenue from the sale of lifetime extended service plans is deferred and recognized over 10 years, with approximately 69% of revenue recognized within the first two years (January 31, 2015: 69%; November 1, 2014: 69%). Revenues related to the optional theft protection are deferred and recognized in proportion to when the expected claims costs will be incurred over the two-year contract period. Zale Jewelry customers are also offered a two-year watch warranty and a one-year warranty that covers breakage. Piercing Pagoda customers are also offered a one-year warranty that covers breakage. Revenue from the two-year watch warranty and one-year breakage warranty is recognized on a straight-line basis over the respective contract terms. The Sterling Jewelers division also sells a Jewelry Replacement Plan (“JRP”). The JRP is designed to protect customers from damage or defects of purchased merchandise for a period of three years. If the purchased merchandise is defective or becomes damaged under normal use in that time period, the item will be replaced. JRP revenue is deferred and recognized on a straight-line basis over the period of expected claims costs. Signet also sells warranty agreements in the capacity of an agent on behalf of a third-party. The commission that Signet receives from the third-party is recognized at the time of sale less an estimate of cancellations based on historical experience.
Reclassification	Reclassification The Company has reclassified the presentation of certain prior year amounts in the statements of cash flows to conform to the current year presentation.
New accounting pronouncements	New accounting pronouncements to be adopted in future periods Revenue recognition In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” The new guidance affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards (for example, insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU No. 2014-09 provides alternative methods of retrospective adoption. In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers-Deferral of the Effective Date.” The new guidance defers the effective date of ASU No. 2014-09 by one year. As a result, ASU No. 2014-09 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, with early adoption permitted for annual periods beginning after December 15, 2016, including interim periods within that annual period. Signet is currently assessing the impact, if any, as well as the available methods of implementation, that the adoption of this accounting pronouncement will have on the Company's financial position or results of operations. Share-based compensation In June 2014, the FASB issued ASU No. 2014-12, “Compensation — Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” The new guidance requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. ASU No. 2014-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015, with early adoption permitted. Signet does not expect the adoption of this guidance to have a material impact on the Company's financial position or results of operations. Debt issuance costs In April 2015, the FASB issued ASU No. 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs.” The new guidance requires that debt issuance costs related to a recognized debt liability be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts. In August 2015, the FASB issued ASU No. 2015-15, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs.” The new guidance provides clarity that the SEC would not object to the deferral and presentation of debt issuance costs related to line-of-credit arrangements as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement. ASU Nos. 2015-03 and 2015-15 are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015, with early adoption permitted. Signet does not expect the adoption of this guidance to have a material impact on the Company's financial position or results of operations. Inventory In July 2015, the FASB issued ASU No. 2015-11, "Inventory (Topic 330): Simplifying the Measurement of Inventory.” The new guidance states that inventory will be measured at the “lower of cost and net realizable value” and options that currently exist for “market value” will be eliminated. The ASU defines net realizable value as the “estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation.” No other changes were made to the current guidance on inventory measurement. ASU 2015-11 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016. Early adoption is permitted and should be applied prospectively. Signet is currently assessing the impact, if any, that that adoption of this guidance will have on the Company's financial position or results of operations. Income Taxes In November 2015, the FASB issued ASU No. 2015-17, “Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes.” The new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. ASU No. 2015-17 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016, with early adoption permitted. Signet does not expect the adoption of this guidance to have a material impact on the Company's financial position or results of operations.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.