Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2018
Accounting Policies [Abstract]
Consolidation, Policy [Policy Text Block]	Consolidation Principles --The consolidated financial statements include the accounts of Twin Disc, Incorporated and its wholly and majority-owned domestic and foreign subsidiaries (the “Company”). Certain foreign subsidiaries are included based on fiscal years ending May 31, to facilitate prompt reporting of consolidated accounts. The Company also has a controlling interest in a Japanese joint venture, which is consolidated based upon a fiscal year ending March 31. All significant intercompany transactions have been eliminated.
Use of Estimates, Policy [Policy Text Block]	Management Estimates-- The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities at the dates of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual amounts could differ from those estimates.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Translation of Foreign Currencies --The financial statements of the Company’s non-U.S. subsidiaries are translated using the current exchange rate for assets and liabilities and the weighted-average exchange rate for the year for revenues and expenses. The resulting translation adjustments are recorded as a component of accumulated other comprehensive loss, which is included in equity. Gains and losses from foreign currency transactions are included in earnings. Included in other income (expense) are foreign currency transaction losses of ( $198 ), ( $318 ) and ( $320 ) in fiscal 2018, 2017 and 2016, respectively.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash --The Company considers all highly liquid investments with original maturities of three months or less to be cash equivalent. Under the Company’s cash management system, cash balances at certain banks are funded when checks are presented for payment. To the extent that checks issued, but not yet presented for payment, exceed the balance on hand at the specific bank against which they were written, the amount of those un-presented checks is included in accounts payable.
Receivables, Policy [Policy Text Block]	Accounts Receivable --These represent trade accounts receivable and are stated net of an allowance for doubtful accounts of $1,478 and $1,519 at June 30, 2018 and 2017, respectively. The Company records an allowance for doubtful accounts provision for certain customers where a risk of default has been specifically identified as well as provisions determined on a general basis when it is believed that some default is probable and estimable. The assessment of likelihood of customer default is based on a variety of factors, including the length of time the receivables are past due, the historical collection experience and existing economic conditions. Various factors may adversely impact our customer’s ability to access sufficient liquidity and capital to fund their operations and render the Company’s estimation of customer defaults inherently uncertain. While the Company believes current allowances for doubtful accounts are adequate, it is possible that these factors may cause higher levels of customer defaults and bad debt expense in future periods.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value of Financial Instruments --The carrying amount reported in the consolidated balance sheets for cash, trade accounts receivable and accounts payable approximate fair value because of the immediate short-term maturity of these financial instruments . If measured at fair value, cash would be classified as Level 1 and all other items listed above would be classified as Level 2 in the fair value hierarchy, as described in Note M. The Company’s borrowings under the revolving loan agreement, which is classified as long-term debt and consists of loans that are routinely borrowed and repaid throughout the year, approximate fair value at June 30, 2018. If measured at fair value in the financial statements, long-term debt (including any current portion) would be classified as Level 2 in the fair value hierarchy, as described in Note M.
Derivatives, Policy [Policy Text Block]	Derivative Financial Instruments - - The Company has written policies and procedures that place all financial instruments under the direction of the Company’s corporate treasury department and restrict all derivative transactions to those intended for hedging purposes. The use of financial instruments for trading purposes is prohibited. The Company uses financial instruments to manage the market risk from changes in foreign exchange rates. Periodically, the Company enters into forward exchange contracts to reduce the earnings and cash flow impact of non-functional currency denominated receivables and payables. These contracts are highly effective in hedging the cash flows attributable to changes in currency exchange rates. Gains and losses resulting from these contracts offset the foreign exchange gains or losses on the underlying assets and liabilities being hedged. The maturities of the forward exchange contracts generally coincide with the settlement dates of the related transactions. Gains and losses on these contracts are recorded in other income (expense) as the changes in the fair value of the contracts are recognized and generally offset the gains and losses on the hedged items in the same period. The primary currency to which the Company was exposed in fiscal 2018 and 2017 was the euro. The Company had no outstanding forward exchange contracts at June 30, 2018. At June 30, 2017, one of the Company’s foreign subsidiaries had three outstanding forward exchange contracts to purchase U.S. dollars in the notional value of $1,050 with a weighted average maturity of 53 days. The fair value of the Company’s contract was a loss of $29 at June 30, 2017.
Inventory, Policy [Policy Text Block]	Inventories --Inventories are valued at the lower of cost or net realizable value. Cost has been determined by the last-in, first -out (LIFO) method for the majority of inventories located in the United States, and by the first -in, first -out (FIFO) method for all other inventories. Management specifically identifies obsolete products and analyzes historical usage, forecasted production based on future orders, demand forecasts, and economic trends, among others, when evaluating the adequacy of the reserve for excess and obsolete inventory.
Property, Plant and Equipment, Policy [Policy Text Block]	Property, Plant and Equipment and Depreciation --Assets are stated at cost. Expenditures for maintenance, repairs and minor renewals are charged against earnings as incurred. Expenditures for major renewals and betterments are capitalized and depreciated. Depreciation is provided on the straight-line method over the estimated useful lives of the assets. The lives assigned to buildings and related improvements range from 10 to 40 years, and the lives assigned to machinery and equipment range from 5 to 15 years. Upon disposal of property, plant and equipment, the cost of the asset and the related accumulated depreciation are removed from the accounts and the resulting gain or loss is reflected in earnings. Fully depreciated assets are not removed from the accounts until physically disposed.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-lived Assets --The Company reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. For property, plant and equipment and other long-lived assets, excluding indefinite-lived intangible assets, the Company performs undiscounted operating cash flow analyses to determine if an impairment exists. If an impairment is determined to exist, any related impairment loss is calculated based on fair value. Fair value is primarily determined using discounted cash flow analyses; however, other methods may be used to determine the fair value, including third party valuations when necessary.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill and Other Intangibles --Goodwill and other indefinite-lived intangible assets, primarily tradenames, are tested for impairment at least annually on the last day of the Company’s fiscal year and more frequently if an event occurs which indicates the asset may be impaired. If applicable, goodwill and other indefinite-lived intangible assets not subject to amortization have been assigned to reporting units for purposes of impairment testing based upon the relative fair value of the asset to each reporting unit. A significant amount of judgment is involved in determining if an indicator of impairment has occurred. Such indicators may include, among others: a significant decline in expected future cash flows; a sustained, significant decline in the Company’s stock price and market capitalization; a significant adverse change in legal factors or in the business climate; unanticipated competition; the testing for recoverability of a significant asset group within a reporting unit; and slower growth rates. Any adverse change in these factors could have a significant impact on the recoverability of these assets and could have a material impact on the Company’s consolidated financial statements. The Company early-adopted the new goodwill guidance, ASU 2017 - 04, during the third quarter of fiscal 2017. Under the new guidance, the goodwill impairment process has been simplified to a one -step approach. The fair value of a reporting unit, as defined, is compared to the carrying value of the reporting unit, including goodwill. The fair value is primarily determined using discounted cash flow analyses which is driven by projected growth rates, and which applies an appropriate market-participant discount rate; the fair value determined is also compared to the value obtained using a market approach from guideline public company multiples. If the carrying amount exceeds the fair value, that difference is recognized as an impairment loss. The Company conducted interim qualitative assessments throughout the year, and its annual assessment for goodwill impairment as of June 30, 2018 and 2017 using updated inputs, including appropriate risk-based, country and company specific weighted average discount rates for the Company’s reporting units. As further described in Note D, these assessments resulted in the Company recognizing a goodwill impairment charge in fiscal 2017. The fair value of the Company’s other intangible assets with indefinite lives, primarily tradenames, is estimated using the relief-from-royalty method, which requires assumptions related to projected revenues; assumed royalty rates that could be payable if the Company did not own the asset; and a discount rate. The Company completed the impairment testing of indefinite-lived intangibles as of June 30, 2018 and concluded there were no impairments. Changes in circumstances, existing at the measurement date or at other times in the future, or in the numerous estimates associated with management’s judgments, assumptions and estimates made in assessing the fair value of goodwill and other indefinite-lived intangibles, could result in an impairment charge in the future. The Company will continue to monitor all significant estimates and impairment indicators, and will perform interim impairment reviews as necessary. Any cost incurred to extend or renew the term of an indefinite lived intangible asset are expensed as incurred.
Income Tax, Policy [Policy Text Block]	Income Taxes --The Company recognizes deferred tax liabilities and assets for the expected future income tax consequences of events that have been recognized in the Company’s financial statements. Under this method, deferred tax liabilities and assets are determined based on the temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities using enacted tax rates in effect in the years in which temporary differences are expected to reverse. Valuation allowances are provided for deferred tax assets where it is considered more likely than not that the Company will not realize the benefit of such assets. The Company evaluates its uncertain tax positions as new information becomes available. Tax benefits are recognized to the extent a position is more likely than not to be sustained upon examination by the taxing authority.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition --Revenue is recognized by the Company when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred and ownership has transferred to the customer; the price to the customer is fixed or determinable; and collectability is reasonably assured. Revenue is recognized at the time product is shipped to the customer, except for certain domestic shipments to overseas customers where revenue is recognized upon receipt by the customer. A significant portion of our consolidated net sales is transacted through a third party distribution network. Sales to third party distributors are subject to the revenue recognition criteria described above. Goods sold to third party distributors are subject to an annual return policy, for which a provision is made at the time of shipment based upon historical experience. As more fully discussed in Recently Issued Accounting Standards, the Company expects to adopt ASU 2014 - 09 in fiscal 2019. Under the new guidance, the Company’s timing of recognizing revenue will change; however, the impact has been determined to be insignificant.
Shipping and Handling Cost, Policy [Policy Text Block]	Shipping and Handling Fees and Costs --The Company records revenue from shipping and handling costs in net sales. The cost associated with shipping and handling of products is reflected in cost of goods sold.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Standards In June 2018, the Financial Accounting Standards Board (“FASB”) issued guidance (ASU 2018 - 07 ) intended to simplify the accounting for share based payments granted to nonemployees. Under the amendments in this guidance, payments to nonemployees would be aligned with the requirements for share based payments granted to employees. The amendments in this guidance are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, ( the Company’s fiscal 2020 ), including interim periods within that fiscal year. The Company is currently evaluating the potential impact of this guidance on the Company’s financial statements and disclosures. In February 2018, the FASB issued guidance (ASU 2018 - 02 ) intended to eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act by allowing a reclassification from accumulated other comprehensive income to retained earnings. The amendments in this guidance are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, ( the Company’s fiscal 2020 ), with early adoption permitted. The Company has not decided when it will adopt this guidance; its adoption will have no impact to total shareholders’ equity. In March 2017, the FASB issued guidance (ASU 2017 - 07 ) intended to improve the presentation of net periodic pension cost and net periodic postretirement cost. This guidance requires that an employer report the service costs component in the same line item 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 statement of operations separately from the service cost component and outside the subtotal of income from operations. The amendments in this guidance are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, ( the Company’s fiscal 2019 ), with early adoption permitted. The Company is currently evaluating the potential impact of this guidance on the Company’s financial statements and disclosures. In October 2016, the FASB issued updated guidance (ASU 2016 - 16 ) that changes the recognition of income tax consequences of an intra-entity transfer of an asset other than inventory. The amendments in this guidance are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 ( the Company’s fiscal 2019 ), with early adoption permitted. The Company is currently evaluating the potential impact of this guidance on the Company’s financial statements and disclosures. In August 2016, the FASB issued updated guidance (ASU 2016 - 15 ) that addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The amendments in this guidance are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 ( the Company’s fiscal 2019 ), with early adoption permitted. The Company is currently evaluating the potential impact of this guidance on the Company’s financial statements and disclosures. In March 2016, the FASB issued updated guidance (ASU 2016 - 09 ) intended to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The Company adopted this standard in the first quarter of fiscal year 2018. As a result of the adoption, excess tax benefits or deficiencies associated with stock-based compensation award activity are recognized in income tax expense in the consolidated statements of operations. In addition, excess tax benefits associated with award activity is reported as cash flows from operating activities along with all other income tax cash flows. The Company has elected to apply this classification change on a prospective basis. The adoption of this guidance did not have a material impact on the Company's financial statements. In February 2016, the FASB issued guidance (ASU 2016 - 02 ) which replaces the existing guidance for leases. The new 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. The guidance is effective for fiscal years beginning after December 15, 2018 ( the Company’s fiscal 2020 ), including interim periods within those fiscal years and requires retrospective application. In preparation for the adoption of this guidance, the Company gathered all active lease contracts from all its locations to assess whether or not they meet the definition of a lease under the new guidance, specifically, whether there is an identified asset in the contract, and whether or not control thereof lies with the Company. The Company assessed the practical expedients that are allowed under the guidance, including the exclusion of lease contracts with terms of twelve months or less. It assessed each contract for the appropriate lease payment components, discount rate, lease terms (dependent on renewal options) and compiled a calculation of the right-of-use assets and operating lease liability amounts that would be recognized on the Company’s balance sheet upon adoption of the guidance. During the fiscal year, the Company concluded its assessment of the impact of the new guidance on its accounting practices, including the operational process changes. It plans to early-adopt the guidance, using the modified retrospective approach, to coincide with its adoption of the new revenue recognition guidance, which is the first quarter of fiscal 2019. At June 30, 2018, the Company would have recognized a right-of-use asset and an operating lease liability of $6,527 as a result of the new guidance. In July 2015, the FASB issued guidance (ASU 2015 - 11 ) intended to simplify the measurement of inventory and to closely align with International Financial Reporting Standards. Current guidance requires inventories to be measured at the lower of cost or market. Under this new guidance, inventories other than those measured under last in first out (“LIFO”) are to be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The Company adopted this guidance, prospectively, in the first fiscal quarter of 2018. The adoption of this guidance did not have an impact on the Company's financial statements. In May 2014, the FASB issued updated guidance (ASU 2014 - 09 ) on revenue from contracts with customers. This revenue recognition guidance supersedes existing guidance, including industry-specific guidance. The core principle is that an entity should recognize revenue to depict the transfer of control over 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. The guidance identifies steps to apply in achieving this principle. This updated guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 ( the Company’s first quarter of fiscal 2019 ). During the fiscal year, the Company concluded its assessment of the impact of the new guidance on its accounting practices. It determined that deferral of revenue is appropriate for certain agreements where the performance of services after product delivery is required. Such services primarily pertain to technical commissioning services by its distribution entities in its marine business, whereby the Company’s technicians calibrate the controls and transmission to ensure proper performance for the customer’s specific application. This service helps identify issues with the ship's design or performance that need to be remediated by the ship builder or other component suppliers prior to the ship being officially accepted into service by the ship buyer. The cumulative effect adjustment of adopting the new standard is not significant to the Company’s results of operations and financial condition. The guidance permits two methods of adoption: full retrospective in which the standard is applied to all of the periods presented, or the modified retrospective approach in which the cumulative effect of initially applying the standard will be recognized as an adjustment to the opening balance of retained earnings. The Company plans to adopt the new standard using the modified retrospective approach and will apply the cumulative effect to its retained earnings balance as of July 1, 2018.