Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Mar. 31, 2020
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 $(0.3) million and $(0.2) million during the three months ended March 31, 2020 and 2019, respectively, and $(0.2) million and $(0.5) million during the nine months ended March 31, 2020 and 2019, 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.
Equity Method Investments [Policy Text Block]	Equity Method Investments During the three months ended March 31, 2020, we entered into a limited partnership investment fund agreement. The primary objective of this partnership is investing in equity and equity-related securities (including convertible debt) of venture growth- stage businesses. We account for the investment in accordance with Topic 323, Investments - Equity Method and Joint Ventures. Our total commitment under this partnership is 5.0 million CAD ($3.5 million). Under the conditions of the equity method investment, unfavorable future changes in market conditions could lead to a potential loss up to the full value of our 5.0 million CAD ($3.5 million) commitment. As of March 31, 2020, the fair value of this investment is 0.5 million CAD ($0.3 million), representing our payment towards the total commitment during the three months ended March 31, 2020, and is recorded in non-current assets in our consolidated balance sheet.
Recently Issued Accounting Pronouncements	(g) New Accounting Pronouncements Adopted in Fiscal 2020 In February 2016, the FASB issued Topic 842. Under the amendment, lessees are 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. We adopted Topic 842 effective July 1, 2019 using the effective date method with a modified retrospective transition approach. Results for reporting periods beginning on or after July 1, 2019 are presented under Topic 842, while prior period amounts were not adjusted and continue to be reported in accordance with the Company’s historic accounting under Topic 840 “Leases.” We elected the package of practical expedients permitted under the transition guidance within the new standard, which allowed the carry forward of historical assessments of whether a contract contains a lease, lease classification and initial direct costs. The most significant impact of the adoption of Topic 842 was the recognition of operating lease right-of-use assets of $28.5 million and current and non-current operating lease liabilities of $7.4 million and $26.5 million, respectively, and the reversal of deferred rent of $6.5 million as of July 1, 2019. The adoption of Topic 842 did not have a material impact on our operating results or cash flows, and there was no impact on our debt covenants. See Note 4, "Leases," to our Unaudited Consolidated Financial Statements for more information on the impact of adopting Topic 842. (h) Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses ("Topic 326"). The amendment changes the impairment model for most financial assets and certain other instruments. Entities will be required to use a model that will result in the earlier recognition of allowances for losses for trade and other receivables, contract assets, held-to-maturity debt securities, loans, and other instruments. Topic 326 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. We are currently evaluating the impact of Topic 326 on our consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes ("Topic 740") - Simplifying the Accounting for Income Taxes. ASU 2019-12 is intended to simplify accounting for income taxes. It removes certain exceptions to the general principles in Topic 740 and amends existing guidance to improve consistent application. ASU 2019-12 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2020. Early adoption is permitted. We are currently evaluating the impact of ASU 2019-12 on our consolidated financial statements.