Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Mar. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Aspen Technology, Inc. and our wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Loss Contingencies	Loss Contingencies We accrue estimated liabilities for loss contingencies arising from claims, assessments, litigation and other sources when it is probable that a liability has been incurred and the amount of the claim, assessment or damages can be reasonably estimated. We believe that we have sufficient accruals to cover any obligations resulting from claims, assessments or litigation that have met these criteria.
Foreign Currency Transactions	Foreign Currency Transactions Foreign currency exchange gains and losses generated from the settlement and remeasurement of transactions denominated in currencies other than the functional currency of our subsidiaries are recognized in our results of operations as incurred as a component of other (expense), net. Net foreign currency exchange losses were $(0.1) million and $(0.5) million during the three and nine months ended March 31, 2019, respectively, and $(0.1) million and $(1.0) million during the three and nine months ended March 31, 2018, respectively.
Research and Development Expense	Research and Development Expense We charge research and development expenditures to expense as the costs are incurred. Research and development expenses consist primarily of personnel expenses related to the creation of new products, enhancements and engineering changes to existing products and costs of acquired technology prior to establishing technological feasibility. We acquired no technology during the three and nine months ended March 31, 2019 and 2018, respectively, that was expensed as research and development expense.
Recently Issued Accounting Pronouncements	(f) New Accounting Pronouncements Adopted in Fiscal 2019 In May 2014, the FASB issued Topic 606, which supersedes the revenue recognition requirements in Revenue Recognition (Topic 605), and requires entities to recognize revenue when they transfer 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. Under the new guidance, an entity is required to evaluate revenue recognition through a five-step process. In applying the principles of Topic 606, more judgment and estimates are required within the revenue recognition process than were required under previous U.S. GAAP, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. We adopted Topic 606 effective July 1, 2018 using the full retrospective method, which required us to adjust the prior periods presented. The adoption of Topic 606 impacted the timing of the license portion of the revenue recognized from our term contracts. Under the new standard, for arrangements that include term-based software licenses bundled with maintenance and support, we are now required to recognize as revenue a portion of the arrangement fee upon delivery of the software license. We recognize as revenue a portion of the arrangement fee related to maintenance and support, professional services, and training over time as the services are provided. Additionally, under the new standard, we capitalize certain direct and incremental commission costs to obtain a contract and amortize such costs over the expected period of benefit, rather than expensing them as incurred in the period that the commissions are earned. See Note 3, "Revenue from Contracts with Customers," to our Unaudited Consolidated Financial Statements for more information on our accounting policies as a result of the adoption of Topic 606. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805) - Clarifying the Definition of a Business. The amendment changes the definition of a business to assist entities in evaluating when a set of transferred assets and activities constitutes a business. We adopted ASU No. 2017-01 effective July 1, 2018. The adoption of ASU No. 2017-01 did not have a material effect on our consolidated financial statements or related disclosures. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740) - Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118. The amendment provides guidance on accounting for the impact of the Tax Cuts and Jobs Act (the “Tax Act”) and allows entities to complete the accounting under ASC 740 within a one-year measurement period from the Tax Act enactment date. This standard is effective upon issuance. The Tax Act has several significant changes that impact all taxpayers, including a transition tax, which is a one-time tax charge on accumulated, undistributed foreign earnings. The calculation of accumulated foreign earnings requires an analysis of each foreign entity’s financial results going back to 1986. We have concluded that we will not be subject to the transition tax associated with our accumulated, undistributed foreign earnings. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract. The amendment aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the amendment. The ASU is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. We adopted ASU No. 2018-15 effective October 1, 2018. The adoption of ASU No. 2018-15 did not have a material effect on our consolidated financial statements or related disclosures. (g) Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). Under the amendment, lessees will be required to recognize virtually all of their leases on the balance sheet, by recording a right-of-use asset and lease liability. The ASU is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted. We are currently evaluating the impact of ASU No. 2016-02 on our consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. The amendment modifies, removes, and adds certain disclosure requirements on fair value measurements. The ASU is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. We are currently evaluating the impact of ASU No. 2018-13 on our consolidated financial statements.