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 consolidated financial statements include our accounts and those of our majority-owned subsidiaries. All significant intercompany balances and transactions are eliminated. Investments in entities of less than 50 percent of the voting stock over which we have significant influence are accounted for on an equity basis. The factors used to determine significant influence include, but are not limited to, our management involvement in the investee, such as hiring and setting compensation for management of the investee, the ability to make operating and capital decisions of the investee, representation on the investee’s board of directors and purchase and supply agreements with the investee. Investments in entities of less than 50 percent of the voting stock in which we do not have significant influence are accounted for on the cost basis.
Use of Estimates in the Preparation of Financial Statements	USE OF ESTIMATES IN THE PREPARATION OF FINANCIAL STATEMENTS In preparing our consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP), we make judgments and estimates about the amounts reflected in our financial statements. As part of our financial reporting process, our management collaborates to determine the necessary information on which to base our judgments and develop estimates used to prepare the financial statements. We use historical experience and available information to make these judgments and estimates. However, different amounts could be reported using different assumptions and in light of different facts and circumstances. Therefore, actual amounts could differ from the estimates reflected in our financial statements.
Cash and Cash Equivalents	CASH AND CASH EQUIVALENTS Cash investments having original maturities of three months or less are considered cash equivalents. Cash equivalents principally consist of investments in money market funds and bank deposits at June 30, 2018.
Accounts Receivable	ACCOUNTS RECEIVABLE We market our products to a diverse customer base throughout the world. Trade credit is extended based upon periodically updated evaluations of each customer’s ability to satisfy its obligations. We make judgments as to our ability to collect outstanding receivables and provide allowances for the portion of receivables when collection becomes doubtful. Accounts receivable reserves are determined based upon an aging of accounts and a review of specific accounts.
Inventory	INVENTORIES We use the last-in, first-out (LIFO) method for determining the cost of a significant portion of our United States ((U.S.) inventories, and they are stated at the lower of cost or market. The cost of the remainder of our inventories is measured using approximate costs determined on the first-in, first-out basis or using the average cost method, and are stated at the lower of cost or net realizable value. When market conditions indicate an excess of carrying costs over market value, a lower of cost or net realizable value provision or a lower of cost or market provision, as applicable, is recorded. Excess and obsolete inventory reserves are established based upon our evaluation of the quantity of inventory on hand relative to demand. The excess and obsolete inventory reserve at June 30, 2018 and 2017 was $31.3 million and $32.1 million, respectively.
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment are carried at cost. Major improvements are capitalized, while maintenance and repairs are expensed as incurred. Retirements and disposals are removed from cost and accumulated depreciation accounts, with the gain or loss reflected in operating income. Interest related to the construction of major facilities is capitalized as part of the construction costs and is depreciated over the facilities' estimated useful lives. Depreciation for financial reporting purposes is computed using the straight-line method over the following estimated useful lives: building and improvements over 15-40 years; machinery and equipment over 4-15 years; furniture and fixtures over 5-10 years and computer hardware and software over 3-5 years. Leased property and equipment under capital leases are depreciated using the straight-line method over the terms of the related leases.
Long Lived Assets	LONG-LIVED ASSETS We evaluate the recoverability of property, plant and equipment and intangible assets that are amortized, whenever events or changes in circumstances indicate the carrying amount of any such assets may not be fully recoverable. Changes in circumstances include technological advances, changes in our business model, capital structure, economic conditions or operating performance. Our evaluation is based upon, among other things, our assumptions about the estimated future undiscounted cash flows these assets are expected to generate. When the sum of the undiscounted cash flows is less than the carrying value of the asset or asset group, we will recognize an impairment loss to the extent that carrying value exceeds fair value. We apply our best judgment when performing these evaluations to determine if a triggering event has occurred, the undiscounted cash flows used to assess recoverability and the fair value of the asset.
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill represents the excess of cost over the fair value of the net assets of acquired companies. Goodwill and other intangible assets with indefinite lives are tested at least annually for impairment. We perform our annual impairment tests during the June quarter in connection with our annual planning process unless there are impairment indicators based on the results of an ongoing cumulative qualitative assessment that warrant a test prior to that quarter. We evaluate the recoverability of goodwill for each of our reporting units by comparing the fair value of each reporting unit with its carrying value. The fair values of our reporting units are determined using a combination of a discounted cash flow analysis and market multiples based upon historical and projected financial information. We apply our best judgment when assessing the reasonableness of the financial projections used to determine the fair value of each reporting unit. We evaluate the recoverability of indefinite-lived intangible assets using a discounted cash flow analysis based on projected financial information. This evaluation is sensitive to changes in market interest rates and other external factors. The majority of our intangible assets with definite lives are amortized on a straight-line basis, while certain customer-related intangible assets are amortized on an accelerated method. Identifiable assets with finite lives are reviewed for impairment when events or circumstances indicate that the carrying value may not be recoverable. 2016 December Quarter Impairment Charge As previously disclosed, we recorded a preliminary non-cash pre-tax impairment charge during the three months ended December 31, 2015 of $106.1 million in the Infrastructure segment, of which $105.7 million was for goodwill and $0.4 million was for an indefinite-lived trademark intangible asset. We also recorded a preliminary non-cash pre-tax impairment charge during the three months ended December 31, 2015 of $2.3 million in the Widia segment for an indefinite-lived trademark intangible asset. These impairment charges are recorded in restructuring and asset impairment charges in our consolidated statements of income. 2016 Divestiture Impact on Goodwill During 2016, we completed the sale of non-core businesses. See Note 4. As a result of this transaction, goodwill decreased by $1.1 million and $6.5 million in our Industrial and Infrastructure segments, respectively. These decreases are recorded in loss on divestiture in our consolidated statements of income. 2016 Divestiture Impact on Other Intangible Assets The divestiture of non-core businesses completed during 2016 resulted in a reduction of $30.0 million in customer-related, $15.4 million in unpatented technology, $5.0 million in indefinite-lived trademarks, $1.1 million in definite-lived trademarks, $0.8 million in technology-based and other and $0.5 million in contract-based. 2017 Reorganization Impact on Goodwill At the beginning of fiscal 2017, we reorganized our operating structure in a manner that changed the composition of our reporting units. The Industrial and Widia reporting units in fiscal 2017 were formed from the fiscal 2016 Industrial reporting unit. In connection with this reporting unit realignment, during the first quarter of fiscal 2017 we updated our goodwill impairment assessment based on a quantitative analysis. We allocated our goodwill from the former Industrial segment to the current Industrial and Widia segments using a relative fair value approach. We evaluated the goodwill of our reporting units immediately prior to and after the realignment and concluded in both cases that there was no impairment. We performed our annual goodwill and indefinite-lived intangible assets impairment test during the June quarter of fiscal 2018 and concluded that there was no impairment.
Pension and Other Postretirement Benefits	PENSION AND OTHER POSTRETIREMENT BENEFITS We sponsor these types of benefit plans for certain employees and retirees. Accounting for the cost of these plans requires the estimation of the cost of the benefits to be provided well into the future and attributing that cost over either the expected work life of employees or over average life of participants participating in these plans, depending on plan status and on participant population. This estimation requires our judgment about the discount rate used to determine these obligations, expected return on plan assets, rate of future compensation increases, rate of future health care costs, withdrawal and mortality rates and participant retirement age. Differences between our estimates and actual results may significantly affect the cost of our obligations under these plans. In the valuation of our pension and other postretirement benefit liabilities, management utilizes various assumptions. Discount rates are derived by identifying a theoretical settlement portfolio of high quality corporate bonds sufficient to provide for a plan’s projected benefit payments. This rate can fluctuate based on changes in the corporate bond yields. The long-term rate of return on plan assets is estimated based on an evaluation of historical returns for each asset category held by the plans, coupled with the current and short-term mix of the investment portfolio. The historical returns are adjusted for expected future market and economic changes. This return will fluctuate based on actual market returns and other economic factors. The rate of future health care costs is based on historical claims and enrollment information projected over the next year and adjusted for administrative charges. This rate is expected to decrease until 2027. Future compensation rates, withdrawal rates and participant retirement age are determined based on historical information. These assumptions are not expected to significantly change. Mortality rates are determined based on a review of published mortality tables.
Earnings Per Share	EARNINGS PER SHARE Basic earnings per share is computed using the weighted average number of shares outstanding during the period, while diluted earnings per share is calculated to reflect the potential dilution that would occur related to the issuance of capital stock under stock option grants, performance awards and restricted stock units. The difference between basic and diluted earnings per share relates solely to the effect of capital stock options, performance awards and restricted stock units. For purposes of determining the number of diluted shares outstanding, weighted average shares outstanding for basic earnings per share calculations were increased due solely to the dilutive effect of unexercised capital stock options, unvested performance awards and unvested restricted stock units by 1.2 million shares and 0.8 million shares for the fiscal year ended June 30, 2018 and 2017, respectively. Unexercised capital stock options, performance awards and restricted stock units of 0.4 million shares and 1.4 million shares for the fiscal year ended June 30, 2018 and 2017, respectively, were not included in the computation of diluted earnings per share because the option exercise price was greater than the average market price, and therefore the inclusion would have been anti-dilutive. In 2016, the effect of unexercised capital stock options, unvested performance awards and unvested restricted stock units was anti-dilutive as a result of a net loss in the periods and therefore has been excluded from diluted shares outstanding as well as from the diluted earnings per share calculation.
Revenue Recognition	REVENUE RECOGNITION We recognize revenue for our products and assembled machines when title and all risks of loss and damages pass to the buyer. Our general conditions of sale explicitly state that the delivery of our products and assembled machines is freight on board shipping point and that title and all risks of loss and damage pass to the buyer upon delivery of the sold products or assembled machines to the common carrier. We recognize revenue related to the sale of specialized assembled machines upon customer acceptance and installation, as installation is deemed essential to the functionality of a specialized assembled machine. Sales of specialized assembled machines were immaterial for 2018, 2017 and 2016. Our general conditions of sale explicitly state that acceptance of the conditions of shipment are considered to have occurred unless written notice of objection is received by Kennametal within 10 calendar days of the date specified on the invoice. We do not ship products or assembled machines unless we have documentation from our customers authorizing shipment. The majority of our products are consumed by our customers in the manufacture of their products. Historically, we have experienced very low levels of returned products and assembled machines and do not consider the effect of returned products and assembled machines to be material. We have recorded an estimated returned goods allowance to provide for any potential returns. We warrant that products and services sold are free from defects in material and workmanship under normal use and service when correctly installed, used and maintained. This warranty terminates 30 days after delivery of the product to the customer and does not apply to products that have been subjected to misuse, abuse, neglect or improper storage, handling or maintenance. Products may be returned to Kennametal, only after inspection and approval by Kennametal and upon receipt by the customer of shipping instructions from Kennametal. We have included an estimated allowance for warranty returns in our returned goods allowance.
Stock-Based Compensation	STOCK-BASED COMPENSATION We recognize stock-based compensation expense for all stock options, restricted stock awards and restricted stock units over the period from the date of grant to the date when the award is no longer contingent on the employee providing additional service (substantive vesting period), net of expected forfeitures. We utilize the Black-Scholes valuation method to establish the fair value of all stock option awards. Time vesting stock units are valued at the market value of the stock on the grant date. Performance vesting stock units with a market condition are valued using a Monte Carlo model. Capital stock options are granted to eligible employees at fair market value at the date of grant. Capital stock options are exercisable under specified conditions for up to 10 years from the date of grant. The Kennametal Inc. Stock and Incentive Plan of 2010, as Amended and Restated on October 22, 2013, and as further amended January 27, 2015 (A/R 2010 Plan) and the Kennametal Inc. 2016 Stock and Incentive Plan (2016 Plan) authorize the issuance of up to 9,500,000 shares of the Company’s capital stock plus any shares remaining unissued under the Kennametal Inc. Stock and Incentive Plan of 2002, as amended (2002 Plan). Under the provisions of the A/R 2010 Plan and 2016 Plan participants may deliver stock, owned by the holder for at least six months, in payment of the option price and receive credit for the fair market value of the shares on the date of delivery. The fair market value of shares delivered during 2018, 2017 and 2016 was immaterial. In addition to stock option grants, the A/R 2010 Plan and the 2016 Plan permit the award of stock appreciation rights, performance share awards, performance unit awards, restricted stock awards, restricted unit awards and share awards to directors, officers and key employees.
Research and Development Costs	RESEARCH AND DEVELOPMENT COSTS Research and development costs of $38.9 million, $38.0 million and $39.4 million in 2018, 2017 and 2016, respectively, were expensed as incurred. These costs are included in operating expense in the consolidated statements of income.
Shipping and Handling Fees and Costs	SHIPPING AND HANDLING FEES AND COSTS All fees billed to customers for shipping and handling are classified as a component of sales. All costs associated with shipping and handling are classified as a component of cost of goods sold.
Income Taxes	INCOME TAXES Deferred income taxes are recognized based on the future income tax effects (using enacted tax laws and rates) of differences in the carrying amounts of assets and liabilities for financial reporting and tax purposes. A valuation allowance is recognized if it is “more likely than not” that some or all of a deferred tax asset will not be realized.
Derivative Instruments and Hedging Activities	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES As part of our financial risk management program, we use certain derivative financial instruments. We do not enter into derivative transactions for speculative purposes and, therefore, hold no derivative instruments for trading purposes. We use derivative financial instruments to provide predictability to the effects of changes in foreign exchange rates on our consolidated results, achieve our targeted mix of fixed and floating interest rates on our outstanding debt. Our objective in managing foreign exchange exposures with derivative instruments is to reduce volatility in cash flow, allowing us to focus more of our attention on business operations. With respect to interest rate management, these derivative instruments allow us to achieve our targeted fixed-to-floating interest rate mix, as a separate decision from funding arrangements, in the bank and public debt markets. We account for derivative instruments as a hedge of the related asset, liability, firm commitment or anticipated transaction, when the derivative is specifically designated as a hedge of such items. We measure hedge effectiveness by assessing the changes in the fair value or expected future cash flows of the hedged item. The ineffective portions are recorded in other expense (income), net. Certain currency forward contracts hedging significant cross-border intercompany loans are considered other derivatives and, therefore, do not qualify for hedge accounting. These contracts are recorded at fair value in the balance sheet, with the offset to other expense (income), net.
Cash Flow Hedges	CASH FLOW HEDGES Currency Forward contracts and range forward contracts (a transaction where both a put option is purchased and a call option is sold) are designated as cash flow hedges and hedge anticipated cash flows from cross-border intercompany sales of products and services. Gains and losses realized on these contracts are recorded in accumulated other comprehensive (loss) income, and are recognized as a component of other expense (income), net when the underlying sale of products or services is recognized into earnings.
Fair Value Hedges	FAIR VALUE HEDGES Interest Rate Fixed-to-floating interest rate swap contracts, designated as fair value hedges, are entered into from time to time to hedge our exposure to fair value fluctuations on a portion of our fixed rate debt. These interest rate swap contracts convert a portion of our fixed rate debt to floating rate debt. When in place, these contracts require periodic settlement, and the difference between amounts to be received and paid under the contracts is recognized in interest expense.
Net Investment Hedges [Policy Text Block]	NET INVESTMENT HEDGES We designate financial instruments as net investment hedges from time to time to hedge the foreign exchange exposure of our net investment in foreign currency-based subsidiaries. The remeasurements of these non-derivatives designated as net investment hedges are calculated each period with changes reported in foreign currency translation adjustment within accumulated other comprehensive loss. Such amounts will remain in accumulated other comprehensive loss unless we complete or substantially complete liquidation or disposal of our investment in the underlying foreign operations.
Currency Translation	CURRENCY TRANSLATION Assets and liabilities of international operations are translated into U.S. dollars using year-end exchange rates, while revenues and expenses are translated at average exchange rates throughout the year. The resulting net translation adjustments are recorded as a component of accumulated other comprehensive loss. The local currency is the functional currency of most of our locations. Losses of $6.4 million and $6.7 million and a gain of $1.6 million from currency transactions were included in other expense (income), net in 2018, 2017 and 2016, respectively.
New Accounting Standards	NEW ACCOUNTING STANDARDS Adopted In March 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-09, "Improvements to Employee Share-Based Payment Accounting," which is intended to simplify equity-based award accounting and presentation. The guidance impacts income tax accounting related to equity-based awards, the classification of awards as either equity or liabilities, and the classification on the statement of cash flows. We adopted this guidance July 1, 2017. The adoption of this guidance resulted in three changes: (1) the increase to deferred tax assets of $1.4 million related to cumulative excess tax benefits previously unrecognized was offset by a valuation allowance, due to the valuation allowance position of our U.S. entity at the time of adoption of this standard; (2) excess tax benefits, previously reported in the financing activities section of the consolidated statements of cash flow, is now reported in the operating activities section, adopted on a prospective basis; therefore, prior period statements of cash flow were not retrospectively adjusted for this provision; and (3) employee taxes paid when Kennametal withholds shares for tax withholding purposes, previously reported in the operating activities section of the consolidated statement of cash flows, are now reported in the financing activities section, adopted on a retrospective basis; therefore, prior period statements of cash flow were retrospectively adjusted for this provision. Cash flow provided by operating activities and cash flow used for financing activities increased by $3.1 million and $3.2 million in 2017 and 2016, respectively. In July 2015, the FASB issued ASU No. 2015-11, "Simplifying the Measurement of Inventory," which requires that inventory other than LIFO be subsequently measured at the lower of cost and net realizable value, as opposed to the previous practice of lower of cost or market. Subsequent measurement is unchanged for inventory measured using LIFO. We adopted this guidance July 1, 2017. Adoption of this guidance did not have a material impact on our consolidated financial statements. Issued In June 2018, the FASB issued ASU No. 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting" which expands the scope of accounting for stock-based compensation to nonemployees. This guidance is effective for Kennametal July 1, 2019. We are in the process of assessing the impact the adoption of this guidance may have on our consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-02, “Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which includes amendments related to the reclassification of the income tax effects of the Tax Cuts and Jobs Act of 2017 (TCJA) to improve the usefulness of information reported to financial statement users. The amendments in this update also require certain disclosures about stranded tax effects. This guidance is optional and is effective for Kennametal July 1, 2019, although early adoption is permitted. We are in the process of assessing the impact the adoption of this guidance may have on our consolidated financial statements and determining whether we will adopt this guidance. In August 2017, the FASB issued ASU No. 2017-12, "Targeted Improvements to Accounting for Hedging Activities," which seeks to improve financial reporting and obtain closer alignment with risk management activities, in addition to simplifying the application of hedge accounting guidance and additional disclosures. This guidance is effective for Kennametal July 1, 2019. We are in the process of assessing the impact the adoption of this guidance may have on our consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, "Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting," which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. This guidance is effective for Kennametal beginning July 1, 2018. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, "Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost," which requires that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. This guidance is effective for Kennametal beginning July 1, 2018, with the amendments to be applied retrospectively. We expect to reclassify combined effects of pension income and postretirement benefit cost of approximately $17 million and $18 million out of operating income and into non-operating income for 2018 and 2017, respectively, when comparative financial information is presented going forward. In October 2016, the FASB issued ASU No. 2016-16, "Intra-Entity Transfers of Assets Other Than Inventory," which clarifies that an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This guidance is effective for Kennametal beginning July 1, 2018. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, "Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force)," which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice with respect to how these are classified in the statement of cash flows. This guidance is effective for Kennametal beginning July 1, 2018. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments," which introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. Beyond other modifications in the update, the scope of this amendment includes valuation of trade receivables. This standard is effective for Kennametal beginning July 1, 2020. We are in the process of assessing the impact the adoption of this guidance will have on our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, "Leases: Topic 842," which replaces the existing guidance in ASC 840, Leases. The standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. This standard is effective for Kennametal beginning July 1, 2019. We have a project team in place that will begin inventorying our leasing arrangements. We are in the process of assessing the impact the adoption of this guidance will have on our consolidated financial statements. As of June 30, 2018, our undiscounted future minimum payments outstanding for lease obligations were approximately $65 million. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers: Topic 606.” This ASU, along with subsequent complementary updates in ASU Nos. 2015-14, 2016-08, 2016-10 and 2016-12 among others, replaces nearly all existing U.S. GAAP guidance on revenue recognition. The standard prescribes a five-step model for recognizing revenue, the application of which will require significant judgment. It also requires additional disclosures. We adopted this standard on July 1, 2018 using the modified retrospective approach. We have a project team that has performed a detailed review of the terms and provisions in customer contracts, and concluded that the new standard will not affect the timing nor measurement of revenue for these contracts in comparison to the results of historical accounting policies and practices. We do not expect the adoption of this guidance to have a material effect on our consolidated financial statements other than additional disclosures.