Summary Of Significant Accounting Policies (Policies)	12 Months Ended
Summary Of Significant Accounting Policies (Policies)	Jun. 30, 2018
Accounting Policies [Abstract]
Principles Of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Lancaster Colony Corporation and our wholly-owned subsidiaries, collectively referred to as “we,” “us,” “our,” “registrant,” or the “Company.” Intercompany transactions and accounts have been eliminated in consolidation. Our fiscal year begins on July 1 and ends on June 30. Unless otherwise noted, references to “year” pertain to our fiscal year; for example, 2018 refers to fiscal 2018, which is the period from July 1, 2017 to June 30, 2018. Effective July 1, 2017, David A. Ciesinski, our President and Chief Operating Officer, succeeded John B. Gerlach, Jr. as Chief Executive Officer (“CEO”). As President and CEO, Mr. Ciesinski became our principal executive officer and chief operating decision maker (“CODM”). This change resulted in modifications to the CODM’s approach to managing the business, assessing performance and allocating resources. Consequently, beginning on July 1, 2017, our segment reporting structure was amended to align with these changes, and our financial results are now presented as two reportable segments: Retail and Foodservice. See Note 10 for additional details. All historical information was retroactively conformed to the current presentation.
Use Of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires that we make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Estimates included in these consolidated financial statements include allowances for customer deductions, net realizable value of inventories, useful lives for the calculation of depreciation and amortization, distribution accruals, pension and postretirement assumptions and self-insurance accruals. Actual results could differ from these estimates.
Cash And Equivalents	Cash and Equivalents We consider all highly liquid investments purchased with original maturities of three months or less to be cash equivalents. The carrying amounts of our cash and equivalents approximate fair value due to their short maturities and are considered level 1 investments, which have quoted market prices in active markets for identical assets. As a result of our cash management system, checks issued but not presented to the banks for payment may create negative book cash balances. When such negative balances exist, they are included in Accrued Liabilities.
Receivables And Related Allowances	Receivables and Related Allowances We evaluate the adequacy of our allowances for customer deductions considering several factors including historical experience, specific trade programs and existing customer relationships. We also provide an allowance for doubtful accounts based on the aging of accounts receivable balances, historical write-off experience and on-going reviews of our trade receivables. Measurement of potential losses requires credit review of existing customer relationships, consideration of historical loss experience, including the need to adjust for current conditions, and judgments about the probable effects of relevant observable data, including present economic conditions such as delinquency rates and the economic health of customers.
Credit Risk	Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and equivalents and trade accounts receivable. By policy, we limit the amount of credit exposure to any one institution or issuer. Our concentration of credit risk with respect to trade accounts receivable is mitigated by our credit evaluation process and by having a large and diverse customer base. However, see Note 10 with respect to our accounts receivable with Walmart Inc. and McLane Company, Inc., a wholesale distribution subsidiary of Berkshire Hathaway, Inc.
Inventories	Inventories Inventories are valued at the lower of cost or net realizable value and are costed by various methods that approximate actual cost on a first-in, first-out basis. Due to the nature of our business, work in process inventory is not a material component of inventory. When necessary, we provide allowances to adjust the carrying value of our inventory to the lower of cost or net realizable value, including any costs to sell or dispose. The determination of whether inventory items are slow moving, obsolete or in excess of needs requires estimates about the future demand for our products. The estimates as to future demand used in the valuation of inventory are subject to the ongoing success of our products and may differ from actual due to factors such as changes in customer and consumer demand.
Property, Plant And Equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost, except for those acquired as part of a business combination, which are recorded at fair value at the time of purchase. We use the straight-line method of computing depreciation for financial reporting purposes based on the estimated useful lives of the corresponding assets. Estimated useful lives for buildings and improvements range generally from 10 to 40 years, machinery and equipment, excluding technology-related equipment, range generally from 3 to 15 years and technology-related equipment range generally from 3 to 5 years. For tax purposes, we generally compute depreciation using accelerated methods.
Long-Lived Assets	Long-Lived Assets We monitor the recoverability of the carrying value of our long-lived assets by periodically considering whether indicators of impairment are present. If such indicators are present, we determine if the assets are recoverable by comparing the sum of the undiscounted future cash flows to the assets’ carrying amounts. Our cash flows are based on historical results adjusted to reflect our best estimate of future market and operating conditions. If the carrying amounts are greater, then the assets are not recoverable. In that instance, we compare the carrying amounts to the fair value to determine the amount of the impairment to be recorded.
Goodwill And Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill is not amortized. It is evaluated annually at April 30 by applying impairment testing procedures. Other intangible assets are amortized on a straight-line basis over their estimated useful lives to Selling, General and Administrative Expenses. We evaluate the future economic benefit of the recorded goodwill and other intangible assets when events or circumstances indicate potential recoverability concerns. Carrying amounts are adjusted appropriately when determined to have been impaired.
Accrued Distribution	Accrued Distribution We incur various freight and other related costs associated with shipping products to our customers and warehouses. We provide accruals for unbilled shipments from carriers utilizing historical or projected freight rates and other relevant information.
Accruals For Self-Insurance	Accruals for Self-Insurance Self-insurance accruals are made for certain claims associated with employee health care, workers’ compensation and general liability insurance. These accruals include estimates that are primarily based on historical loss development factors.
Shareholders' Equity	Shareholders’ Equity We are authorized to issue 3,050,000 shares of preferred stock consisting of 750,000 shares of Class A Participating Preferred Stock with $1.00 par value, 1,150,000 shares of Class B Voting Preferred Stock without par value and 1,150,000 shares of Class C Nonvoting Preferred Stock without par value. Our Board of Directors approved a share repurchase authorization of 2,000,000 common shares in November 2010.
Revenue Recognition	Revenue Recognition We recognize revenue upon transfer of title and risk of loss, provided that evidence of an arrangement exists, pricing is fixed or determinable, and collectability is probable. Net sales are recorded net of estimated sales discounts, returns, trade promotions and certain other sales incentives, including coupon redemptions and rebates.
Advertising Expense	Advertising Expense We expense advertising as it is incurred.
Research And Development Costs	Research and Development Costs We expense research and development costs as they are incurred.
Distribution Costs	Distribution Costs Distribution fees billed to customers are included in Net Sales, while our distribution costs incurred are included in Cost of Sales.
Stock-Based Employee Compensation Plans	Stock-Based Employee Compensation Plans We account for our stock-based employee compensation plans in accordance with GAAP for stock-based compensation, which requires the measurement and recognition of the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The cost of the employee services is recognized as compensation expense over the period that an employee provides service in exchange for the award, which is typically the vesting period.
Income Taxes	Income Taxes Our income tax expense, deferred tax assets and liabilities and reserves for unrecognized tax benefits reflect management’s best assessment of estimated future taxes to be paid. We are subject to income taxes in numerous domestic jurisdictions. Our annual effective tax rate is determined based on our income, statutory tax rates and the permanent tax impacts of items treated differently for tax purposes than for financial reporting purposes. Tax law requires certain items be included in the tax return at different times than the items are reflected in the financial statements. Some of these differences are permanent, such as expenses that are not deductible in our tax return, and some differences are temporary, reversing over time, such as depreciation expense. These temporary differences create deferred tax assets and liabilities. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. See further discussion in Note 9. Realization of certain deferred tax assets is dependent upon generating sufficient taxable income in the appropriate jurisdiction prior to the expiration of the carryforward periods. Although realization is not assured, management believes it is more likely than not that our deferred tax assets will be realized and thus we have not recorded any valuation allowance for the years ended June 30, 2018 or 2017. In accordance with accounting literature related to uncertainty in income taxes, tax benefits and liabilities from uncertain tax positions that are recognized in the financial statements are measured based on the largest attribute that has a greater than fifty percent likelihood of being realized upon ultimate settlement.
Earnings Per Share	Earnings Per Share Earnings per share (“EPS”) is computed based on the weighted average number of shares of common stock and common stock equivalents (restricted stock and stock-settled stock appreciation rights) outstanding during each period. Unvested shares of restricted stock granted to employees are considered participating securities since employees receive nonforfeitable dividends prior to vesting and, therefore, are included in the earnings allocation in computing EPS under the two-class method. Basic EPS excludes dilution and is computed by dividing income available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted EPS is computed by dividing income available to common shareholders by the diluted weighted average number of common shares outstanding during the period, which includes the dilutive potential common shares associated with nonparticipating restricted stock and stock-settled stock appreciation rights.
Comprehensive Income And Accumulated Other Comprehensive Income (Loss)	Comprehensive Income and Accumulated Other Comprehensive Income (Loss) Comprehensive income includes changes in equity that result from transactions and economic events from non-owner sources. Comprehensive income is composed of two subsets – net income and other comprehensive income (loss). Included in other comprehensive income (loss) are pension and postretirement benefits adjustments.
Recently Issued And Recently Adopted Accounting Standards	Recently Issued Accounting Standards In March 2017, the Financial Accounting Standards Board (“FASB”) issued new accounting guidance to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost by disaggregating the service cost component from the other components of net periodic benefit cost. The amendments require an employer to present service cost in the same line item(s) as compensation costs for the pertinent employees whereas the other components of net periodic benefit cost must be reported separately from service cost and outside of income from operations. The amendments also allow only the service cost component to be eligible for capitalization. The amendments require retrospective application for the income statement presentation provisions and prospective application for the capitalization of the service cost component. However, as a result of prior years’ restructuring activities, we no longer have any active employees continuing to accrue service cost. Therefore, the service cost provisions are not applicable to us, and we expect only changes in classification on the income statement. We will adopt the new guidance on July 1, 2018. In May 2014, the FASB issued new accounting guidance for the recognition of revenue and issued subsequent clarifications of this new guidance in 2016 and 2017. The core principle of the new guidance states 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. This model is based on a control approach rather than the current risks and rewards model. We have completed a review of selected customer contracts and evaluated the impact of the new standard on certain common practices currently employed by us and by other manufacturers of consumer products. We have also finalized our assessment of the impact this standard will have on our accounting policies, processes, system requirements, internal controls and disclosures using internal resources and the assistance of a third party. We will adopt the new guidance on July 1, 2018 using a modified retrospective approach, but we will not record a cumulative-effect adjustment from initially applying the standard as the adoption will not have a material impact on our financial position or results of operations. There will be additional required disclosures in the notes to the consolidated financial statements upon adoption. In February 2016, the FASB issued new accounting guidance to require lessees to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months and issued subsequent clarifications of this new guidance in 2018. This guidance retains the two classifications of a lease as either an operating or finance lease (previously referred to as a capital lease). Both lease classifications require the lessee to record a right-of-use asset and a lease liability based upon the present value of the lease payments. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-of-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The guidance requires expanded qualitative and quantitative disclosures, including additional information about the amounts recorded in the consolidated financial statements. The guidance will be effective for us in fiscal 2020 including interim periods. In July 2018, the FASB issued guidance that allows for an alternate transition method whereby companies can recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption rather than restating comparative periods. We are currently evaluating the impact of this guidance. Recently Adopted Accounting Standards In February 2018, the FASB issued new accounting guidance to allow a reclassification from accumulated other comprehensive income/loss to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 (“Tax Act”). GAAP requires deferred tax assets and liabilities to be adjusted for the effect of a change in tax rates with the effect of the change included in income from continuing operations even when the related income tax effects of items in accumulated other comprehensive income/loss were originally recognized in other comprehensive income rather than in income from continuing operations. We adopted the new guidance on a prospective basis in the quarter ended March 31, 2018 and elected to reclassify these stranded tax effects resulting from the Tax Act from accumulated other comprehensive loss to retained earnings in the period of adoption. These tax effects related to the impact of the change in the federal income tax rate on pension and postretirement benefit amounts remaining in accumulated other comprehensive loss, and the reclassification resulted in a net increase in accumulated other comprehensive loss of $1.9 million and a corresponding increase in retained earnings. Our accounting policy is to release stranded tax effects from accumulated other comprehensive loss. As this guidance only relates to balance sheet classification, there was no impact on the Consolidated Statements of Income. In March 2016, the FASB issued new accounting guidance to simplify the accounting for stock-based compensation. The amendments include changes to the accounting for share-based payment transactions, including: the inclusion of the tax consequences related to stock-based compensation within the computation of income tax expense versus equity; the classification of awards as either equity or liabilities; and the classification of share-based activity on the statement of cash flows. The adoption may result in increased volatility to our quarterly and annual income tax expense and resulting net income in future periods dependent upon, among other variables, the price of our common stock and the timing and volume of share-based payment award activity such as employee exercises of stock-settled stock appreciation rights and vesting of restricted stock awards. We adopted the new guidance on July 1, 2017 and elected to continue to estimate forfeitures. The adoption of this guidance resulted in 1) the prospective recognition of windfall tax benefits and shortfall tax deficiencies in income tax expense; 2) the retrospective reclassification of windfall tax benefits on the Consolidated Statements of Cash Flows from financing activities to operating activities; and 3) the retrospective reclassification of employee tax withholdings on the Consolidated Statements of Cash Flows from operating activities to financing activities. There was no material impact on our consolidated financial statements as a result of this adoption.