Nature of Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Aug. 29, 2018
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Luby’s, Inc. is based in Houston, Texas. As of August 29, 2018, the Company owned and operated 146 restaurants, with 114 in Texas and the remainder in other states. In addition, the Company received royalties from 105 franchises as of August 29, 2018 located primarily throughout the United States. The Company’s owned and franchised restaurant locations are convenient to shopping and business developments, as well as, to residential areas. Accordingly, the restaurants appeal to a variety of customers at breakfast, lunch, and dinner. Culinary Contract Services consists of contract arrangements to manage food services for clients operating in primarily four lines of business: healthcare; senior living; business; and venues.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Luby’s, Inc. and its wholly owned subsidiaries. Luby’s, Inc. was restructured into a holding company on February 1, 1997, at which time all of the operating assets were transferred to Luby’s Restaurants Limited Partnership, a Texas limited partnership consisting of two wholly owned, indirect corporate subsidiaries of the Company. On July 9, 2010, Luby’s Restaurants Limited Partnership was converted into Luby’s Fuddruckers Restaurants, LLC, a Texas limited liability company (“LFR”). Unless the context indicates otherwise, the word “Company” as used herein includes Luby’s, Inc., LFR, and the consolidated subsidiaries of Luby’s, Inc. All significant intercompany accounts and transactions have been eliminated in consolidation.
Reportable Segments	Reportable Segments Each restaurant is an operating segment because operating results and cash flow can be determined for each restaurant which is regularly reviewed by the chief operating decision maker. The Company has three reportable segments: Company-owned restaurants, franchise operations, and Culinary Contract Services (“CCS”). Company-owned restaurants are aggregated into one reportable segment because the nature of the products and services, the production processes, the customers, the methods used to distribute the products and services, and the nature of the regulatory environment are alike.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include highly liquid investments such as money market funds that have a maturity of three months or less. The Company’s bank account balances are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000 at each institution. However, balances in money market fund accounts are not insured. Amounts in transit from credit card companies are also considered cash equivalents because they are both short-term and highly liquid in nature and are typically converted to cash within three days of the sales transaction.
Trade Accounts and Other Receivables, net	Trade Accounts and Other Receivables, net Receivables consist principally of amounts due from franchises, culinary contract service clients, catering customers and restaurant food sales to corporations. Receivables are recorded at the invoiced amount. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance based on historical loss experience for CCS clients, catering customers and restaurant sales to corporations and, for CCS receivables and franchise royalty and marketing and advertising receivables, the Company also considers the franchisees’ and CCS clients’ unsecured default status. The Company periodically reviews its allowance for doubtful accounts. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote.
Inventories	Inventories Food and supply inventories are stated at the lower of cost (first-in, first-out) or net realizable value.
Property Held for Sale	Property Held for Sale The Company periodically reviews long-lived assets against its plans to retain or ultimately dispose of properties. If the Company decides to dispose of a property, it will be moved to property held for sale and actively marketed. Property held for sale is recorded at amounts not in excess of what management currently expects to receive upon sale, less costs of disposal. Depreciation on assets moved to property held for sale is discontinued and gains are not recognized until the properties are sold.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Impairment losses are recorded on long-lived assets used in operations when indicators of impairment are present and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount. The Company evaluates impairments on a restaurant-by-restaurant basis and uses cash flow results and other market conditions as indicators of impairment.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs include costs incurred in connection with the arrangement of long-term financing agreements. The debt issuance costs associated with the Term Loan are presented on the Balance Sheet as a direct deduction from long-term debt. The debt issue costs associated with the Revolver are presented on the Balance Sheet as an asset. These costs are amortized using the effective interest method over the respective term of the debt to which they specifically relate.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying value of cash and cash equivalents, trade accounts and other receivables, accounts payable and accrued expenses approximates fair value based on the short-term nature of these accounts. The carrying value of credit facility debt also approximates fair value based on its recent renewal.
Self-Insurance Accrued Expenses	Self-Insurance Accrued Expenses The Company self-insures a significant portion of expected losses under its workers’ compensation, employee injury and general liability programs. Accrued liabilities have been recorded based on estimates of the ultimate costs to settle incurred claims, both reported and not yet reported. These recorded estimated liabilities are based on judgments and independent actuarial estimates, which include the use of claim development factors based on loss history; economic conditions; the frequency or severity of claims and claim development patterns; and claim reserve management settlement practices. Effective January 1, 2018, we maintain a self-insured health benefit plan which provides medical and prescription drug benefits to certain of our employees electing coverage under the plan. Our exposure is limited by individual and aggregate stop loss limits per 3rd party insurance carriers. We record expenses under the plan based on estimates of the costs of expected claims, administrative costs and stop-loss insurance premiums. Our self-insurance expense is accrued based upon the aggregate of the expected liability for reported claims and the estimated liability for claims incurred but not reported, based on historical claims experience provided by our 3rd party insurance advisors, adjusted as necessary based upon management’s reasoned judgment. Actual employee medical claims expense may differ from estimated loss provisions based on historical experience.
Revenue Recognition	Revenue Recognition Revenue from restaurant sales is recognized when food and beverage products are sold. Unearned revenues are recorded as a liability for gift cards that have been sold but not yet redeemed and are recorded at their expected redemption value. When gift cards are redeemed, revenue is recognized, and unearned revenue is reduced. Revenue from culinary contract services is recognized when services are provided and reimbursable costs are incurred within contractual terms. Revenue from franchise royalties is recognized each fiscal period based on contractual royalty rates applied to the franchise’s restaurant sales each fiscal period. Royalties are accrued as earned and are calculated each period based on the franchisee’s reported sales. Area development fees and franchise fees are recognized as revenue when the Company has performed all material obligations and initial services. Area development fees are recognized proportionately with the opening of each new restaurant, which generally occurs upon the opening of the new restaurant. Until earned, these fees are accounted for as an accrued liability.
Cost of CCS	Cost of CCS The cost of CCS includes all food, payroll and related expenses, other operating expenses, and selling, general and administrative expenses related to culinary contract service sales. All depreciation and amortization, property disposal, and asset impairment expenses associated with CCS are reported within those respective lines as applicable.
Cost of Franchise Operations	Cost of Franchise Operations The cost of franchise operations includes all food, payroll and related expenses, other operating expenses, and selling, general and administrative expenses related to franchise operations sales. All depreciation and amortization, property disposal, and asset impairment expenses associated with franchise operations are reported within those respective lines as applicable.
Marketing and Advertising Expenses	Marketing and Advertising Expenses Marketing and advertising costs are expensed as incurred. Total advertising expense included in other operating expenses and selling, general and administrative expense was $4.1 million, $5.7 million, and $6.3 million in fiscal 2018, 2017, and 2016, respectively. We record advertising attributable to local store marketing and local community involvement efforts in other operating expenses; we record advertising attributable to our brand identity, our promotional offers, and our other marketing messages intended to drive guest awareness of our brands, in selling, general, and administrative expenses. We believe this separation of our marketing and advertising costs assists with measurement of the profitability of individual restaurant locations by associating only the local store marketing efforts with the operations of each restaurant.
Depreciation and Amortization	Depreciation and Amortization Property and equipment are recorded at cost. The Company depreciates the cost of equipment over its estimated useful life using the straight-line method. Leasehold improvements are amortized over the lesser of their estimated useful lives or the related lease terms. Depreciation of buildings is provided on a straight-line basis over the estimated useful lives.
Opening Costs	Opening Costs Opening costs are expenditures related to the opening of new restaurants through its opening periods, other than those for capital assets. Such costs are charged to expense when incurred.
Operating Leases	Operating Leases The Company leases restaurant and administrative facilities and administrative equipment under operating leases. Building lease agreements generally include rent holidays, rent escalation clauses and contingent rent provisions for a percentage of sales in excess of specified levels. Contingent rental expenses are recognized prior to the achievement of a specified target, provided that the achievement of the target is considered probable. Most of the Company’s lease agreements include renewal periods at the Company’s option. The Company recognizes rent holiday periods and scheduled rent increases on a straight-line basis over the lease term beginning with the date the Company takes possession of the leased space.
Income Taxes	Income Taxes The estimated future income tax effects of temporary differences between the tax bases of assets and liabilities and amounts reported in the accompanying consolidated balance sheets, as well as operating loss and tax credit carrybacks and carryforwards are recorded. Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities (temporary differences) and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is recognized if, based on the weight of available evidence, it is more likely than not a portion or all of the deferred tax asset will not be recognized. During fiscal 2018, management concluded to increase their valuation allowance to reduce fully the Company’s net deferred tax asset balances, net of deferred tax liabilities, including through the fiscal year ended August 29, 2018. Management makes judgments regarding the interpretation of tax laws that might be challenged upon an audit and cause changes to previous estimates of tax liability. In addition, the Company operates within multiple taxing jurisdictions and is subject to audit in these jurisdictions as well as by the Internal Revenue Service (“IRS”). In management’s opinion, adequate provisions for income taxes have been made for all open tax years. The potential outcomes of examinations are regularly assessed in determining the adequacy of the provision for income taxes and income tax liabilities. Management believes that adequate provisions have been made for reasonably possible outcomes related to uncertain tax matters.
Sales Taxes	Sales Taxes The Company presents sales taxes on a net basis (excluded from revenue).
Discontinued Operations	Discontinued Operations Management evaluates unit closures for presentation in discontinued operations following guidance from ASC 205-20-55. To qualify for presentation as a discontinued operation, management determines if the closure or exit of a business location or activity meets the following conditions: (1) the operations and cash flows of the component have been (or will be) eliminated from the ongoing operations of the entity as a result of the disposal transaction and (2) there will not be any significant continuing involvement in the operations of the component after the disposal transaction. To evaluate whether these conditions are met, management considers whether the cash flows lost will not be recovered and generated by the ongoing entity, the level of guest traffic and sales transfer, the significance of the number of locations closed and expectancy of cash flow replacement by sales from new and existing locations, as well as the level of continuing involvement in the disposed operation. Operating and non-operating results of these locations are then classified and reported as discontinued operations of all periods presented. As of fiscal 2016, management evaluates unit closures for presentation in discontinued operations following guidance from ASU 2014-08. Beginning in fiscal 2016, in accordance with ASU No. 2014-08, the Company will only report the disposal of a component or a group of components of the Company in discontinued operations if the disposal of the components or group of components represents a strategic shift that has or will have a major effect on the Company’s operations and financial results. Adoption of this standard did not have a material impact on our consolidated financial statements.
Share-Based Compensation	Share-Based Compensation Share-based compensation expense is estimated for equity awards at fair value at the grant date. The Company determines fair value of restricted stock awards based on the average of the high and low price of its common stock on the date awarded by the Board of Directors. The Company determines the fair value of stock option awards using a Black-Scholes option pricing model. The Black-Scholes option pricing model requires various judgmental assumptions including the expected dividend yield, stock price volatility, and the expected life of the award. If any of the assumptions used in the model change significantly, share-based compensation expense may differ materially in the future, from that recorded in the current period. The fair value of performance share based award liabilities are estimated based on a Monte Carlo simulation model. For further discussion, see Note 16, “Share-Based Compensation,” below.
Earnings Per Share	Earnings Per Share Basic income per share is computed by dividing net income by the weighted-average number of shares outstanding, including restricted stock units, during each period presented. For the calculation of diluted net income per share, the basic weighted average number of shares is increased by the dilutive effect of stock options, determined using the treasury stock method.
Accounting Periods	Accounting Periods The Company’s fiscal year ends on the last Wednesday in August. Accordingly, each fiscal year normally consists of 13 four-week periods, or accounting periods, accounting for 364 days in the aggregate. However, every fifth or sixth year, we have a fiscal year that consists of 53 weeks, accounting for 371 days in the aggregate; fiscal 2016 was such a year. Each of the first three quarters of each fiscal year, prior to fiscal 2016, consisted of three four-week periods, while the fourth quarter normally consists of four four-week periods. Beginning in fiscal 2016, we changed our fiscal quarter ending dates with the first fiscal quarter end was extended by one accounting period and the fiscal fourth quarter was reduced by one accounting period. The purpose of this change is in part to minimize the Thanksgiving calendar shift by extending the first fiscal quarter until after Thanksgiving. With this change in fiscal quarter ending dates, our first quarter is 16 weeks, and the remaining three quarters will typically be 12 weeks in length. The fourth fiscal quarter will be 13 weeks in certain fiscal years to adjust for our standard 52 week, or 364 day, fiscal year compared to the 365 day calendar year. Fiscal 2016 was such a year where the fourth quarter included 13 weeks, resulting in a 53 week fiscal year. Comparability between quarters may be affected by varying lengths of the quarters, as well as the seasonality associated with the restaurant business.
Use of Estimates	Use of Estimates In preparing financial statements in conformity with accounting principles generally accepted in the United States of America, management is required 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 revenues and expenses during the reporting period. Actual results could differ from these estimates.
Recently Adopted Accounting Pronouncements and New Accounting Pronouncements - to be Adopted	Recently Adopted Accounting Pronouncements In August 2014, the FASB issued ASU No 2014-15. The amendments in ASU 2014-15 are intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. Under GAAP, financial statements are prepared under the presumption that the reporting organization will continue to operate as a going concern, except in limited circumstances. The going concern basis of accounting is critical to financial reporting because it establishes the fundamental basis for measuring and classifying assets and liabilities. Currently, GAAP lacks guidance about management’s responsibility to evaluate whether there is substantial doubt about the organization’s ability to continue as a going concern or to provide related footnote disclosures. This ASU provides guidance to an organization’s management, with principles and definitions that are intended to reduce diversity in the timing and content of disclosures that are commonly provided by organizations today in the financial statement footnotes. The Company adopted ASU 2014-15 in the quarter ended December 20, 2017. The provisions of ASU 2014-15 present that the Company’s continuation as a going concern is dependent on its ability to generate sufficient cash flows from operations to meet its obligations and obtain alternative financing to refund and repay the current debt owed under its Credit Agreement. Current conditions raise substantial doubt about the Company’s ability to continue as a going concern. See Note 2. Management's Assessment of Going Concern for further discussion on the impact to the Company. In July 2015, the FASB issued ASU 2015-11, Simplifying the Measurement of Inventory (Topic 330). This update requires inventory within the scope of the standard to be measured at the lower of cost and net realizable value. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The Company adopted ASU 2015-11 in the quarter ended December 20, 2017. The provisions of ASU 2015-11 did not have a material effect on the Company's financial condition, results of operations, or cash flows. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740). This update requires that deferred tax liabilities and assets be classified as noncurrent in a classified balance sheet. The Company adopted ASU 2015-17 in the quarter ended December 20, 2017. The provisions of ASU 2015-17 did not have a material effect on the Company's financial condition, results of operations, or cash flows. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718). This update was issued as part of the FASB’s simplification initiative and affects all entities that issue share-based payment awards to their employees. The amendments in this update cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess tax benefits on the statement of cash flows, an accounting policy election for forfeitures, the amount an employer can withhold to cover income taxes and still qualify for equity classification and the classification of those taxes paid on the statement of cash flows. The Company adopted ASU 2016-09 in the quarter ended December 20, 2017. The provisions of ASU 2016-09 did not have a material effect on the Company's financial condition, results of operations, or cash flows. New Accounting Pronouncements - "to be Adopted" In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This update provides a single, comprehensive revenue recognition model that requires a company 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. During 2015, 2016, and 2017, the FASB issued various amendments which provide additional clarification and implementation guidance on ASU 2014-09 (collectively, with ASU 2014-09, “ASC 606”). Specifically, these amendments clarify how an entity should identify the specified good or service for the principal versus agent evaluation and how it should apply the control principle to certain types of arrangements, clarify how an entity should identify performance obligations and licensing implementation guidance, as well as account for shipping and handling fees and freight service, assess collectability, present sales tax, treat non-cash consideration, and account for completed and modified contracts at the time of transition. The new guidance requires enhanced disclosures, including revenue recognition policies to identify performance obligations to customers and significant judgments in measurement and recognition. The effective date and transition requirements for ASC 606 is for fiscal years, and for interim periods within those years, beginning after December 15, 2017. The guidance allows for either a full retrospective or modified retrospective transition method. We will adopt this guidance effective with the first quarter of fiscal year 2019, which is the first fiscal quarter of the annual reporting period beginning after December 15, 2017. We will apply the modified retrospective transition method, which involves recording a cumulative adjustment for the impact of transitioning to the new guidance on the transition date and disclosing in the year of adoption the amount by which each financial statement line item was affected by applying ASC 606 and an explanation of significant changes. We will use the practical expedient to apply ASC 606 only to contracts not completed by the beginning of fiscal year 2019 (the date of the initial application of ASC 606 and amendments). We do not expect the adoption of ASC 606 to have an impact on its recognition of revenues from Company owned stores (except for recognition of breakage on gift card sales discussed below), revenues from our culinary contract services, vending revenue or ongoing franchise royalty fees, which are based on a percentage of franchise sales. We expect the adoption of ASC 606 will require us to recognize initial and renewal franchise and development fees on a straight-line basis over the term of the franchise agreement, which is usually 20 years. Historically, we have recognized revenue from initial franchise and development fees upon the opening of a franchised restaurant when we have completed all our material obligations and initial services. We do not expect this change to have a material impact on our franchise revenues. The cumulative effect adjustment to be recorded to retained earnings upon adoption is expected to consist of an increase in current accrued expenses and other liabilities of approximately $0.6 million associated with the fees received through the end of fiscal year 2018 that would have been deferred and recognized over the term of each respective franchise agreement if the new guidance had been applied in the past. This liability will be recognized as revenue in future periods over the remaining term of the respective franchise agreements. ASC 606 will also change our reporting of marketing and advertising fund (“MAF”) contributions from franchisees and the related marketing and advertising expenditures. Under the current guidance, we do not reflect MAF contributions from franchisees and MAF expenditures in our statements of operations. Although the gross amounts of our revenues and expenses will be impacted by the recognition of franchisee MAF fund contributions and related expenditures of MAF funds we manage, increases to gross revenues and expenses will not result in a material net impact to our statement of operations. Additionally, ASC 606 requires gift card breakage to be recognized as revenue in proportion to the pattern of gift card redemptions exercised by our customers. Currently, we record breakage income within other (expense) income (and not within revenue) when it is deemed remote that the unused gift card balance will be redeemed. We do not expect this change to have a material impact on our Company owned store revenues. The cumulative effect adjustment to be recorded to retained earnings upon adoption is expected to consist of a reduction to current accrued expenses and other liabilities within a range of approximately $2.0 million to $3.1 million associated with the adjustment to unearned gift card revenue if the new guidance had been applied in the past. We are further evaluating the effect this guidance will have on our consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). In January and July 2018, The FASB issued ASC 2018-01, 2018-10 and 2018-11, which were targeted improvements to ASU 2016-02 (collectively, with ASC 2016-02, “ASC 842”) and provided entities with an additional (and optional) transition method to adopt the new leases standard. ASC 842 requires a lessee to recognize on the balance sheet a liability to make lease payments and a corresponding right-of-use asset. The update also requires additional disclosures about the amount, timing and uncertainty of cash flows arising from leases. This update is effective for annual and interim periods beginning after December 15, 2018, which will require us to adopt these provisions in the first quarter of fiscal 2020, and requires a modified retrospective transition approach with application in all comparative periods presented (the “comparative method”), or alternatively, as of the effective date as the date of initial application without restating comparative period financial statements (the “effective date method”). The new guidance also provides several practical expedients and policies that companies may elect under either transition method. Based on a preliminary assessment, the Company expects that most of its operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on our consolidated balance sheet. The Company is continuing its assessment of the impact of adoption, which may identify additional impacts this standard will have on its consolidated financial statements and related disclosures and has not yet determined the method of adoption. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230). This update provides clarification regarding how certain cash receipts and cash payment are presented and classified in the statement of cash flows. This update addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This update is effective for annual and interim periods beginning after December 15, 2017, which will require us to adopt these provisions in the first quarter of fiscal 2019 using a retrospective approach. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements.
Subsequent Events	Subsequent Events Events subsequent to the Company’s fiscal year ended August 29, 2018 through the date of issuance of the financial statements are evaluated to determine if the nature and significance of the events warrant inclusion in the Company’s consolidated financial statements.