Basis of Presentation	6 Months Ended
Mar. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation General The accompanying unaudited condensed consolidated financial statements include the accounts of PTC Inc. and its wholly owned subsidiaries and have been prepared by management in accordance with accounting principles generally accepted in the United States of America and in accordance with the rules and regulations of the Securities and Exchange Commission regarding interim financial reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles for complete financial statements. While we believe that the disclosures presented are adequate in order to make the information not misleading, these unaudited quarterly financial statements should be read in conjunction with our annual consolidated financial statements and related notes included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, consisting only of those of a normal recurring nature, necessary for a fair statement of our financial position, results of operations and cash flows at the dates and for the periods indicated. The September 30, 2018 Consolidated Balance Sheet included herein is derived from our audited consolidated financial statements. Unless otherwise indicated, all references to a year mean our fiscal year, which ends on September 30. Our fiscal quarters end on a Saturday following a thirteen-week calendar and may result in different quarter end dates year to year. The second quarter of 2019 ended on March 30, 2019 and the second quarter of 2018 ended on March 31, 2018. The results of operations for the six months ended March 30, 2019 are not necessarily indicative of the results expected for the remainder of the fiscal year. Changes in Presentation and Reclassifications On October 1, 2018, we adopted ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASC 606). Results for reporting periods beginning on or after October 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with the guidance provided by ASC 985-605, Software-Revenue Recognition and revenues for non-software deliverables in accordance with ASC 605-25, Revenue Recognition, Multiple-Element Arrangements (ASC 605). In connection with the adoption of ASC 606, we changed our presentation of the statement of operations to reflect revenue and associated costs as license, support and cloud services, and professional services. For the prior year period, all components of subscription licenses (including support) are included in license revenue. Prior to our adoption of ASC 606, revenues from subscription licenses and support thereon were not separated and were previously included in subscription revenue in our consolidated statement of operations since we did not have VSOE of fair value for support on subscription sales. In addition, revenue and costs associated with our cloud services, which are immaterial and were previously reported in subscription revenue, are classified as support and cloud services for all periods presented. Effective at the beginning of fiscal 2019, in accordance with the adoption of ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, all non-service net periodic pension costs are now presented in Other income (expense), net on the Consolidated Statement of Operations. The prior period non-service net periodic pension cost amounts have been reclassified for comparability. Effective at the beginning of fiscal 2019, in accordance with the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, restricted cash is now included with cash and cash equivalents in the net cash increase (decrease), beginning of period total amount and end of period total amount on the Consolidated Statements of Cash Flows. The prior period restricted cash amounts have been reclassified for comparability. As of March 30, 2019 and September 30, 2018, $1.1 million of restricted cash was included in other current assets. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements Revenue Recognition On October 1, 2018, we adopted ASC 606, which supersedes substantially all existing revenue recognition guidance under U.S. GAAP. We adopted ASC 606 using the modified retrospective method, under which the cumulative effect of initially applying ASC 606 was recorded as a reduction to accumulated deficit with no restatement of comparative periods. The core principle of ASC 606 is to recognize revenue when promised goods or services are transferred to a customer in an amount that reflects the consideration that is expected to be received for those goods or services. Under the new guidance, an entity is required to evaluate revenue recognition through a five-step process: (1) identifying a contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when (or as) the entity satisfies a performance obligation. The standard also requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In applying the principles of ASC 606, more judgment and estimates are required within the revenue recognition process than is required under previous U.S. GAAP, including identifying performance obligations, estimating the amount of variable consideration to include in the transaction price, and estimating the value of each performance obligation to allocate the total transaction price to each separate performance obligation. The most significant impact of ASC 606 relates to accounting for our subscription arrangements that include term-based on-premise software licenses bundled with support. Under previous GAAP (ASC 605, through September 30, 2018), revenue attributable to these subscription licenses was recognized ratably over the term of the arrangement because VSOE does not exist for the undelivered support element as it is not sold separately. Under the new standard, the requirement to have VSOE for undelivered elements to enable the separation of revenue for the delivered software licenses is eliminated. Accordingly, under the new standard we recognize as revenue a portion of the subscription fee upon delivery of the software license. Revenue recognition related to our perpetual licenses and related support contracts, professional services and cloud offerings is substantially unchanged, with support and cloud revenue being recorded ratably over the contract term. Due to the complexity of certain of our contracts, the actual revenue recognition treatment required under the new standard may be dependent on contract-specific terms and, therefore, may vary in some instances. Upon implementation of the new standard in fiscal 2019, we made prospective revisions to contract terms with our customers that will result in shortening the initial, non-cancellable term of our multi-year subscriptions to one year for contract periods that begin on or after October 1, 2018. This change will result in annual contractual periods for most of our software subscriptions, the license portion of which will be recognized at the beginning of each annual contract period and the support portion of which will be recognized ratably over the one-year contractual period. As a result, we anticipate one year of subscription revenue will be recognized for each contract each year; however, more of the revenue will be recognized in the quarter that the contract period begins and less will be recognized in the subsequent three quarters of the contract than under ASC 605. Under the modified retrospective method, we evaluated each contract that was ongoing on October 1, 2018 as if that contract had been accounted for under ASC 606 from contract inception. Some license revenue related to subscription arrangements that would have been recognized in future periods under current GAAP was recast under ASC 606 as if the revenue had been recognized in prior periods. Under this transition method, we did not adjust historical reported revenue amounts. Instead, the revenue that would have been recognized under this method prior to the adoption date was recorded as an adjustment to accumulated deficit and will not be recognized as revenue in future periods as previously expected. Because license revenue associated with subscription contracts is recognized up front instead of over time under ASC 606, a material portion of our deferred revenue was adjusted to accumulated deficit upon adoption. Another significant provision under ASC 606 includes the capitalization and amortization of costs associated with obtaining a contract, such as sales commissions. Prior to October 1, 2018, we expensed commissions in the period incurred. Under ASC 606, direct and incremental costs to acquire a contract are capitalized and amortized using a systematic basis over the pattern of transfer of the goods and services to which the asset relates. Refer to Note 2. Revenue from Contracts with Customers for further detail about the impact of the adoption of ASC 606 and further disclosures. Income Taxes In October 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The purpose of ASU 2016-16 is to simplify the income tax accounting of an intra-entity transfer of an asset other than inventory and to record its effect when the transfer occurs. We adopted this amendment beginning in the first quarter of 2019 using the modified retrospective method with a cumulative effect adjustment to accumulated deficit of $72.3 million, with a corresponding increase of $75.3 million to deferred tax assets, $6.0 million decrease to income tax assets and a $3.0 million decrease to income tax liabilities. The adjustment primarily relates to deductible amortization of intangible assets in Ireland. Post adoption, our effective tax rate no longer includes the benefit of this amortization. Pension Accounting In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which provides guidance on the capitalization, presentation and disclosure of net benefit costs related to post-retirement benefit plans. We adopted the new guidance in the first quarter of 2019 on a full retrospective basis, which resulted in the retrospective reclassification of $0.2 million and $0.3 million of non-service net periodic pension cost for the three and six months ended March 31, 2018, respectively, from line items within cost of revenue and operating expenses into Other income (expense), net on the Consolidated Statement of Operations. Equity Investments In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which provides guidance for the recognition, measurement, presentation, and disclosure of financial assets and liabilities and requires equity securities to be measured at fair value, unless the measurement alternative method has been elected for equity investments without readily determinable fair values. Adoption of this guidance in the first quarter of fiscal 2019 did not have a material impact on our consolidated financial statements. Restricted Cash In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new guidance requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the Statement of Cash Flows. Adoption of this guidance in the first quarter of fiscal 2019 did not have a material impact on our consolidated financial statements. Pending Accounting Pronouncements Derivative Financial Instruments In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging (Topic 815) Targeted Improvements to Accounting for Hedging Activities", which amends and simplifies existing guidance to allow companies to more accurately present the economic effects of risk management activities in the financial statements. The guidance is effective for annual reporting periods beginning after December 15, 2018 (our fiscal 2020) including interim reporting periods within those annual reporting periods and early adoption is permitted. We are currently evaluating the impact of the new guidance on our consolidated financial statements. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will replace the existing guidance in ASC 840, Leases. The updated standard aims to increase transparency and comparability among organizations by requiring lessees to recognize lease assets and lease liabilities on the balance sheet and to disclose important information about leasing arrangements. ASU 2016-02 is effective for annual periods beginning after December 15, 2018 (our fiscal 2020) and interim periods within those annual periods. Early adoption is permitted and modified retrospective application is required. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

Basis of Presentation

General

The accompanying unaudited condensed consolidated financial statements include the accounts of PTC Inc. and its wholly owned subsidiaries and have been prepared by management in accordance with accounting principles generally accepted in the United States of America and in accordance with the rules and regulations of the Securities and Exchange Commission regarding interim financial reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles for complete financial statements. While we believe that the disclosures presented are adequate in order to make the information not misleading, these unaudited quarterly financial statements should be read in conjunction with our annual consolidated financial statements and related notes included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, consisting only of those of a normal recurring nature, necessary for a fair statement of our financial position, results of operations and cash flows at the dates and for the periods indicated. The September 30, 2018 Consolidated Balance Sheet included herein is derived from our audited consolidated financial statements.

Unless otherwise indicated, all references to a year mean our fiscal year, which ends on September 30. Our fiscal quarters end on a Saturday following a thirteen-week calendar and may result in different quarter end dates year to year. The second quarter of 2019 ended on March 30, 2019 and the second quarter of 2018 ended on March 31, 2018. The results of operations for the six months ended March 30, 2019 are not necessarily indicative of the results expected for the remainder of the fiscal year.

Changes in Presentation and Reclassifications

On October 1, 2018, we adopted ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASC 606). Results for reporting periods beginning on or after October 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with the guidance provided by ASC 985-605, Software-Revenue Recognition and revenues for non-software deliverables in accordance with ASC 605-25, Revenue Recognition, Multiple-Element Arrangements (ASC 605). In connection with the adoption of ASC 606, we changed our presentation of the statement of operations to reflect revenue and associated costs as license, support and cloud services, and professional services. For the prior year period, all components of subscription licenses (including support) are included in license revenue. Prior to our adoption of ASC 606, revenues from subscription licenses and support thereon were not separated and were previously included in subscription revenue in our consolidated statement of operations since we did not have VSOE of fair value for support on subscription sales. In addition, revenue and costs associated with our cloud services, which are immaterial and were previously reported in subscription revenue, are classified as support and cloud services for all periods presented.

Effective at the beginning of fiscal 2019, in accordance with the adoption of ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, all non-service net periodic pension costs are now presented in Other income (expense), net on the Consolidated Statement of Operations. The prior period non-service net periodic pension cost amounts have been reclassified for comparability.

Effective at the beginning of fiscal 2019, in accordance with the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, restricted cash is now included with cash and cash equivalents in the net cash increase (decrease), beginning of period total amount and end of period total amount on the Consolidated Statements of Cash Flows. The prior period restricted cash amounts have been reclassified for comparability. As of March 30, 2019 and September 30, 2018, $1.1 million of restricted cash was included in other current assets.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Revenue Recognition

On October 1, 2018, we adopted ASC 606, which supersedes substantially all existing revenue recognition guidance under U.S. GAAP. We adopted ASC 606 using the modified retrospective method, under which the cumulative effect of initially applying ASC 606 was recorded as a reduction to accumulated deficit with no restatement of comparative periods.

The core principle of ASC 606 is to recognize revenue when promised goods or services are transferred to a customer in an amount that reflects the consideration that is expected to be received for those goods or services. Under the new guidance, an entity is required to evaluate revenue recognition through a five-step process: (1) identifying a contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when (or as) the entity satisfies a performance obligation. The standard also requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In applying the principles of ASC 606, more judgment and estimates are required within the revenue recognition process than is required under previous U.S. GAAP, including identifying performance obligations, estimating the amount of variable consideration to include in the transaction price, and estimating the value of each performance obligation to allocate the total transaction price to each separate performance obligation.

The most significant impact of ASC 606 relates to accounting for our subscription arrangements that include term-based on-premise software licenses bundled with support. Under previous GAAP (ASC 605, through September 30, 2018), revenue attributable to these subscription licenses was recognized ratably over the term of the arrangement because VSOE does not exist for the undelivered support element as it is not sold separately. Under the new standard, the requirement to have VSOE for undelivered elements to enable the separation of revenue for the delivered software licenses is eliminated. Accordingly, under the new standard we recognize as revenue a portion of the subscription fee upon delivery of the software license. Revenue recognition related to our perpetual licenses and related support contracts, professional services and cloud offerings is substantially unchanged, with support and cloud revenue being recorded ratably over the contract term. Due to the complexity of certain of our contracts, the actual revenue recognition treatment required under the new standard may be dependent on contract-specific terms and, therefore, may vary in some instances.

Upon implementation of the new standard in fiscal 2019, we made prospective revisions to contract terms with our customers that will result in shortening the initial, non-cancellable term of our multi-year subscriptions to one year for contract periods that begin on or after October 1, 2018. This change will result in annual contractual periods for most of our software subscriptions, the license portion of which will be recognized at the beginning of each annual contract period and the support portion of which will be recognized ratably over the one-year contractual period. As a result, we anticipate one year of subscription revenue will be recognized for each contract each year; however, more of the revenue will be recognized in the quarter that the contract period begins and less will be recognized in the subsequent three quarters of the contract than under ASC 605.

Under the modified retrospective method, we evaluated each contract that was ongoing on October 1, 2018 as if that contract had been accounted for under ASC 606 from contract inception. Some license revenue related to subscription arrangements that would have been recognized in future periods under current GAAP was recast under ASC 606 as if the revenue had been recognized in prior periods. Under this transition method, we did not adjust historical reported revenue amounts. Instead, the revenue that would have been recognized under this method prior to the adoption date was recorded as an adjustment to accumulated deficit and will not be recognized as revenue in future periods as previously expected. Because license revenue associated with subscription contracts is recognized up front instead of over time under ASC 606, a material portion of our deferred revenue was adjusted to accumulated deficit upon adoption.

Another significant provision under ASC 606 includes the capitalization and amortization of costs associated with obtaining a contract, such as sales commissions. Prior to October 1, 2018, we expensed commissions in the period incurred. Under ASC 606, direct and incremental costs to acquire a contract are capitalized and amortized using a systematic basis over the pattern of transfer of the goods and services to which the asset relates.

Refer to Note 2. Revenue from Contracts with Customers for further detail about the impact of the adoption of ASC 606 and further disclosures.

Income Taxes

In October 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The purpose of ASU 2016-16 is to simplify the income tax accounting of an intra-entity transfer of an asset other than inventory and to record its effect when the transfer occurs. We adopted this amendment beginning in the first quarter of 2019 using the modified retrospective method with a cumulative effect adjustment to accumulated deficit of $72.3 million, with a corresponding increase of $75.3 million to deferred tax assets, $6.0 million decrease to income tax assets and a $3.0 million decrease to income tax liabilities. The adjustment primarily relates to deductible amortization of intangible assets in Ireland. Post adoption, our effective tax rate no longer includes the benefit of this amortization.

Pension Accounting

In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which provides guidance on the capitalization, presentation and disclosure of net benefit costs related to post-retirement benefit plans. We adopted the new guidance in the first quarter of 2019 on a full retrospective basis, which resulted in the retrospective reclassification of $0.2 million and $0.3 million of non-service net periodic pension cost for the three and six months ended March 31, 2018, respectively, from line items within cost of revenue and operating expenses into Other income (expense), net on the Consolidated Statement of Operations.

Equity Investments

In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which provides guidance for the recognition, measurement, presentation, and disclosure of financial assets and liabilities and requires equity securities to be measured at fair value, unless the measurement alternative method has been elected for equity investments without readily determinable fair values. Adoption of this guidance in the first quarter of fiscal 2019 did not have a material impact on our consolidated financial statements.

Restricted Cash

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new guidance requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the Statement of Cash Flows. Adoption of this guidance in the first quarter of fiscal 2019 did not have a material impact on our consolidated financial statements.

Pending Accounting Pronouncements

Derivative Financial Instruments

In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging (Topic 815) Targeted Improvements to Accounting for Hedging Activities", which amends and simplifies existing guidance to allow companies to more accurately present the economic effects of risk management activities in the financial statements. The guidance is effective for annual reporting periods beginning after December 15, 2018 (our fiscal 2020) including interim reporting periods within those annual reporting periods and early adoption is permitted. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

Leases

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will replace the existing guidance in ASC 840, Leases. The updated standard aims to increase transparency and comparability among organizations by requiring lessees to recognize lease assets and lease liabilities on the balance sheet and to disclose important information about leasing arrangements. ASU 2016-02 is effective for annual periods beginning after December 15, 2018 (our fiscal 2020) and interim periods within those annual periods. Early adoption is permitted and modified retrospective application is required. We are currently evaluating the impact of the new guidance on our consolidated financial statements.