Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 09, 2017
Accounting Policies [Abstract]
Statement of Registrant	Statement of Registrant The accompanying Condensed Consolidated Financial Statements of SUPERVALU INC. (“Supervalu”, the “Company”, “we”, “us”, or “our”) for the second quarters ended September 9, 2017 and September 10, 2016 are unaudited and, in the opinion of management, contain all adjustments that are of a normal and recurring nature necessary to present fairly the financial condition, results of operations and cash flows for such periods. The Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and related notes in Supervalu’s Annual Report on Form 10-K for the fiscal year ended February 25, 2017. The results of operations for the second quarter ended September 9, 2017 are not necessarily indicative of the results expected for the full year.
Accounting Policies	Accounting Policies The summary of significant accounting policies is included in the Notes to Consolidated Financial Statements set forth in Supervalu’s Annual Report on Form 10-K for the fiscal year ended February 25, 2017.
Fiscal Year	Fiscal Year Supervalu operates on a 52/53 week fiscal year basis, with its fiscal year ending on the last Saturday in February. References to the second quarters of fiscal 2018 and 2017 relate to the 12 week fiscal quarters ended September 9, 2017 and September 10, 2016, respectively. References to fiscal 2018 and 2017 year-to-date relate to the 28 week fiscal periods ended September 9, 2017 and September 10, 2016, respectively.
Use of Estimates	Use of Estimates The preparation of Supervalu’s Condensed Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and 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. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents Supervalu considers all highly liquid investments with a maturity of three months or less at the time of purchase to be cash equivalents. Supervalu’s banking arrangements allow Supervalu to fund outstanding checks when presented to the financial institution for payment. Supervalu funds all intraday bank balance overdrafts during the same business day. Checks outstanding in excess of bank balances create net book overdrafts, which are recorded in Accounts payable in the Condensed Consolidated Balance Sheets and are reflected as an operating activity in the Condensed Consolidated Statements of Cash Flows. As of September 9, 2017 and February 25, 2017, Supervalu had net book overdrafts of $166 and $91, respectively.
Inventories, Net	Inventories, Net Inventories are valued at the lower of cost or market. Substantially all of Supervalu’s inventories consist of finished goods and a substantial portion of Supervalu’s inventories have a last-in, first-out (“LIFO”) reserve applied. Interim LIFO calculations are based on Supervalu’s estimates of expected year-end inventory levels and costs, as the actual valuation of inventory under the LIFO method is computed at the end of each year based on the inventory levels and costs at that time. If the first-in, first-out method had been used, Inventories, net would have been higher by approximately $218 at September 9, 2017 and $216 at February 25, 2017. Supervalu recorded a LIFO charge of $1 and $1 for the second quarters ended September 9, 2017 and September 10, 2016, respectively. Supervalu recorded a LIFO charge of $3 and $2 for fiscal 2018 and 2017 year-to-date, respectively.
Recently Issued Accounting Standards	Recently Adopted Accounting Standards In March 2016, the Financial Accounting Standards Board (the "FASB") issued authoritative guidance under Accounting Standards Update ("ASU") 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 provides for simplification of several aspects of the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. Supervalu adopted this guidance in the first quarter of fiscal 2018, which resulted in $5 of additional income tax expense that would have been recorded as an adjustment to Additional paid-in-capital under previous authoritative guidance. The adoption resulted in the presentation of payments for shares traded for taxes within financing activities, which resulted in the retrospective revision of the Condensed Consolidated Statements of Cash Flows. In addition, estimated forfeitures continued to be recorded as stock-based compensation expense. Recently Issued Accounting Standards In March 2017, the FASB issued authoritative guidance under ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. ASU 2017-07 changes how benefit plan costs for defined benefit pension and other postretirement benefit plans are presented in the statement of operations. Supervalu is required to adopt this new guidance in the first quarter of fiscal 2019. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. Supervalu is currently evaluating the potential impact of adoption of this standard on its consolidated financial statements. In August 2016, the FASB issued authoritative guidance under ASU 2016-15, Statement of Cash Flows (Topic 320): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 clarifies how certain cash receipts and payments should be presented in the statement of cash flows. Supervalu is required to adopt this new guidance in the first quarter of fiscal 2019. Supervalu is currently evaluating the potential impact of adoption of this standard on its consolidated financial statements. In June 2016, the FASB issued authoritative guidance under ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking “expected loss” model that will replace today’s “incurred loss” model and generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses in a manner similar to current practice, except that the losses will be recognized as an allowance. Supervalu is required to adopt this new guidance in the first quarter of fiscal 2021. Supervalu is currently evaluating the potential impact of adoption of this standard on its consolidated financial statements. In February 2016, the FASB issued authoritative guidance under ASU 2016-02, Leases (Topic 842). ASU 2016-02 provides new comprehensive lease accounting guidance that supersedes existing lease guidance. Upon adoption of ASU 2016-02, Supervalu will be required to recognize most leases on its balance sheet at the beginning of the earliest comparative period presented with a corresponding adjustment to stockholders’ equity (deficit). ASU 2016-02 requires Supervalu to capitalize most current operating lease obligations as right-of-use assets with a corresponding liability based on the present value of future operating leases. Criteria for distinguishing leases between finance and operating are substantially similar to criteria for distinguishing between capital leases and operating leases in existing lease guidance. Supervalu is required to adopt this new guidance in the first quarter of fiscal 2020. Supervalu is currently evaluating the potential impact of adoption of this standard on its consolidated financial statements. For a quantification of Supervalu’s off-balance sheet operating leases subject to capitalization under ASU 2016-02, other than those reserved for as a closed property and certain agreements that may be deemed leases under the new authoritative guidance, refer to total operating lease obligations within Note 9—Leases in the Notes to Consolidated Financial Statements included in Part II, Item 8 of Supervalu's Annual Report on Form 10-K for the fiscal year ended February 25, 2017. In January 2016, the FASB issued authoritative guidance under ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 revises the classification, measurement and disclosure of investments in equity securities. Supervalu is required to adopt this new guidance in the first quarter of fiscal 2019. Supervalu is currently evaluating the potential impact of adoption of this standard on its consolidated financial statements. In May 2014, the FASB issued authoritative guidance under ASU 2014-09, Revenue from Contracts with Customers (Topic 606): Revenue from Contracts with Customers. ASU 2014-09 supersedes existing revenue recognition requirements and provides a new comprehensive revenue recognition model that requires entities to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. The new guidance will be adopted by Supervalu during the first quarter of fiscal 2019, as permitted by ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date. The adoption will include updates as provided under ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net); ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing; ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients; and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. Adoption is allowed by either the full retrospective or modified retrospective approach. Supervalu is currently evaluating which of the alternative approaches it will apply and the potential impact of adoption of the revised revenue standards on its consolidated financial statements. Supervalu believes that there will be few, if any, substantial changes to its Retail segment. Arrangements where Supervalu has determined it was a principal versus an agent are expected to remain relatively unchanged. Distribution contracts within Wholesale contain certain immaterial promises for goods or services that Supervalu believes will be immaterial in the context of the contracts. Supervalu expects to complete its evaluation in fiscal 2018. Upon conclusion of the revised revenue assessment, Supervalu will determine whether to adopt the guidance under the full retrospective or modified retrospective approach.

Disclosure of accounting policy for cash and cash equivalents, including the policy for determining which items are treated as cash equivalents. Other information that may be disclosed includes (1) the nature of any restrictions on the entity's use of its cash and cash equivalents, (2) whether the entity's cash and cash equivalents are insured or expose the entity to credit risk, (3) the classification of any negative balance accounts (overdrafts), and (4) the carrying basis of cash equivalents (for example, at cost) and whether the carrying amount of cash equivalents approximates fair value.