Basis of Presentation	3 Months Ended
Dec. 30, 2017
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 of 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, 2017. 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. Unless otherwise indicated, all references to a year mean our fiscal year, which ends on September 30. The September 30, 2017 Consolidated Balance Sheet included herein is derived from our audited consolidated financial statements. Our fiscal year 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 first quarter of 2018 ended on December 30, 2017 and the first quarter of 2017 ended on December 31, 2016. The results of operations for the three months ended December 30, 2017 are not necessarily indicative of the results expected for the remainder of the fiscal year. Reclassifications Effective with the beginning of the third quarter of 2017, we are reporting cost of license and subscription revenue separately from cost of support revenue and are presenting cost of revenue in three categories: 1) cost of license and subscription revenue, 2) cost of support revenue, and 3) cost of professional services revenue. Cost of license and subscription includes the cost of perpetual and subscription licenses; cost of support includes the cost of supporting both perpetual and subscription licenses. Costs of revenue for previous periods in the accompanying Consolidated Statements of Operations are presented on a basis consistent with the current period presentation. Effective the beginning of fiscal 2018, in accordance with the adoption of ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, excess tax benefits are now classified as an operating activity on the statement of cash flows rather than as a financing activity. The prior period excess tax benefits have been reclassified for comparability. Segments Through fiscal 2017, we had three operating and reportable segments: (1) the Solutions Group, which included license, subscription, support and cloud services revenue for our core CAD, SLM and ePLM products; (2) the IoT Group, which included license, subscription, support and cloud services revenue for our IoT, analytics and augmented reality solutions; and (3) Professional Services, which included consulting, implementation and training revenue. With a change in our organizational structure to streamline our operations, we merged our Solution Group segment with our IoT Group segment and revised the information that our chief executive officer, who is also our chief operating decision maker ("CODM"), regularly reviews for purposes of allocating resources and assessing performance. As a result, effective with the beginning of the first quarter of 2018, we are changing our operating and reportable segments from three to two: (1) Software Products, which includes license, subscription and related support revenue (including updates and technical support) for all our products; and (2) Professional Services, which includes consulting, implementation and training services. Revenue and operating income in Note 10. Segment Information have been reclassified to conform to the current period presentation. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. We have elected to adopt these amendments beginning in the first quarter of 2018. Starting this quarter, stock-based compensation excess tax benefits or deficiencies are reflected in the Consolidated Statements of Operations as a component of the provision for income taxes when the awards vest or are settled, whereas they previously were recognized in equity. Upon adoption, under the modified retrospective transition method, we recognized the previously unrecognized excess tax benefits of $37.0 million as increases in deferred tax assets for tax loss carryovers and tax credits, almost all of which were offset by a valuation allowance. The standard also increases the amount of shares an employer can withhold for tax purposes without triggering liability accounting and clarifies that all cash payments made on an employee's behalf for withheld shares should be presented as a financing activity in the statements of cash flows, which is consistent with our historical classification. The new standard for minimum statutory withholding tax requirements had no impact to opening retained earnings as of October 1, 2017 as we do not intend to withhold more than the minimum statutory requirements. Additionally, on our Consolidated Statements of Cash Flows excess tax benefits from stock-based awards will no longer be separately classified as a financing activity apart from other income tax, and will be presented as an operating activity. As a result of the adoption of ASU 2016-09, the Consolidated Statement of Cash Flows for the three months ended December 31, 2016 was adjusted as follows: a $0.1 million increase to net cash used by operating activities and a $0.1 million decrease to net cash used in financing activities. Finally, we have elected to account for forfeitures as they occur, rather than estimate expected forfeitures, which resulted in a cumulative effect adjustment of $0.7 million to reduce retained earnings as of October 1, 2017. Pending Accounting Pronouncements Derivative Financial Instruments In August 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-12, "Derivatives and Hedging (Topic 815) Targeted Improvements to Accounting for Hedging Activities", which amends and simplifies existing guidance in order 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. Income Taxes In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). 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. The guidance is effective for annual reporting periods beginning after December 15, 2017 (our fiscal 2019) 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. We expect to record a net deferred tax asset of approximately $77 million upon adoption, primarily relating to deductible amortization of intangible assets in Ireland. Post adoption, our effective tax rate will no longer include the benefit of this amortization which is reflected in our effective tax rate reconciliation under the current guidance. 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. Revenue Recognition In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09). ASU 2014-09 supersedes nearly all existing revenue recognition guidance under U.S. GAAP. The FASB has also issued additional standards to provide clarification and implementation guidance on ASU 2014-09. The core principle of ASU 2014-09 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 ASU 2014-09, it is possible more judgment and estimates may be required within the revenue recognition process than is required under existing 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. ASU 2014-09 is effective for us in our first quarter of fiscal 2019. Companies may adopt ASU 2014-09 using either the retrospective method, under which each prior reporting period is presented under ASU 2014-09, with the option to elect certain permitted practical expedients, or the modified retrospective method, under which a company adopts ASU 2014-09 from the beginning of the year of initial application with no restatement of comparative periods, with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application, with certain additional required disclosures. We currently expect to adopt ASU 2014-09 using the modified retrospective method. While we are continuing to assess the impact of the new standard, we currently believe the most significant impact relates to accounting for our subscription arrangements that include term-based on-premise software licenses bundled with support. Under current GAAP, the revenue attributable to these subscription licenses is 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 will be required to recognize as revenue a portion of the subscription fee upon delivery of the software license. We currently expect revenue related to our perpetual licenses and related support contracts, professional services and cloud offerings to remain substantially unchanged. 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 expect to make 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 contracts entered into or renewed after October 1, 2018. This change will result in annual contractual periods for the majority of our software subscriptions, the license portion of which will be recognized at the beginning of each annual contract period upon delivery of the licenses 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 the current accounting rules. Under the modified retrospective method, we will evaluate each contract that is ongoing on the adoption date as if that contract had been accounted for under ASU 2014-09 from contract inception. Some license revenue related to subscription arrangements that would have been recognized in future periods under current GAAP will be recast under ASU 2014-09 as if the revenue had been recognized in prior periods. Under this transition method, we will not adjust historical reported revenue amounts. Instead, the revenue that would have been recognized under this method prior to the adoption date will be an adjustment to retained earnings and will not be recognized as revenue in future periods as previously planned. Because we expect that license revenue associated with subscription contracts will be recognized up front instead of over time under ASU 2014-09, we expect some portion of our deferred revenue to be adjusted to retained earnings upon adoption, which could be a material amount. During the first year of adoption, we will disclose the amount of this retained earnings adjustment and intend to provide supplemental disclosure of how this revenue would have been recognized under the current rules. Another significant provision under ASU 2014-09 includes the capitalization and amortization of costs associated with obtaining a contract, such as sales commissions. Currently, we expense sales commissions in the period incurred. Under ASU 2014-09, 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. While we are continuing to assess the impact of this provision of ASU 2014-09, we likely will be required to capitalize incremental costs such as commissions and amortize those costs over the period the capitalized assets are expected to contribute to future cash flows. Furthermore, we have made and will continue to make investments in systems and processes to enable timely and accurate reporting under the new standard. We currently expect that necessary operational and internal control structural changes will be implemented prior to the adoption date.

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 of 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, 2017. 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. Unless otherwise indicated, all references to a year mean our fiscal year, which ends on September 30. The September 30, 2017 Consolidated Balance Sheet included herein is derived from our audited consolidated financial statements.

Our fiscal year 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 first quarter of 2018 ended on December 30, 2017 and the first quarter of 2017 ended on December 31, 2016. The results of operations for the three months ended December 30, 2017 are not necessarily indicative of the results expected for the remainder of the fiscal year.

Reclassifications

Effective with the beginning of the third quarter of 2017, we are reporting cost of license and subscription revenue separately from cost of support revenue and are presenting cost of revenue in three categories: 1) cost of license and subscription revenue, 2) cost of support revenue, and 3) cost of professional services revenue. Cost of license and subscription includes the cost of perpetual and subscription licenses; cost of support includes the cost of supporting both perpetual and subscription licenses. Costs of revenue for previous periods in the accompanying Consolidated Statements of Operations are presented on a basis consistent with the current period presentation.

Effective the beginning of fiscal 2018, in accordance with the adoption of ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, excess tax benefits are now classified as an operating activity on the statement of cash flows rather than as a financing activity. The prior period excess tax benefits have been reclassified for comparability.

Segments

Through fiscal 2017, we had three operating and reportable segments: (1) the Solutions Group, which included license, subscription, support and cloud services revenue for our core CAD, SLM and ePLM products; (2) the IoT Group, which included license, subscription, support and cloud services revenue for our IoT, analytics and augmented reality solutions; and (3) Professional Services, which included consulting, implementation and training revenue.

With a change in our organizational structure to streamline our operations, we merged our Solution Group segment with our IoT Group segment and revised the information that our chief executive officer, who is also our chief operating decision maker ("CODM"), regularly reviews for purposes of allocating resources and assessing performance. As a result, effective with the beginning of the first quarter of 2018, we are changing our operating and reportable segments from three to two: (1) Software Products, which includes license, subscription and related support revenue (including updates and technical support) for all our products; and (2) Professional Services, which includes consulting, implementation and training services.

Revenue and operating income in Note 10. Segment Information have been reclassified to conform to the current period presentation.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Stock Compensation

In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. We have elected to adopt these amendments beginning in the first quarter of 2018.

Starting this quarter, stock-based compensation excess tax benefits or deficiencies are reflected in the Consolidated Statements of Operations as a component of the provision for income taxes when the awards vest or are settled, whereas they previously were recognized in equity. Upon adoption, under the modified retrospective transition method, we recognized the previously unrecognized excess tax benefits of $37.0 million as increases in deferred tax assets for tax loss carryovers and tax credits, almost all of which were offset by a valuation allowance.

The standard also increases the amount of shares an employer can withhold for tax purposes without triggering liability accounting and clarifies that all cash payments made on an employee's behalf for withheld shares should be presented as a financing activity in the statements of cash flows, which is consistent with our historical classification. The new standard for minimum statutory withholding tax requirements had no impact to opening retained earnings as of October 1, 2017 as we do not intend to withhold more than the minimum statutory requirements.

Additionally, on our Consolidated Statements of Cash Flows excess tax benefits from stock-based awards will no longer be separately classified as a financing activity apart from other income tax, and will be presented as an operating activity. As a result of the adoption of ASU 2016-09, the Consolidated Statement of Cash Flows for the three months ended December 31, 2016 was adjusted as follows: a $0.1 million increase to net cash used by operating activities and a $0.1 million decrease to net cash used in financing activities.

Finally, we have elected to account for forfeitures as they occur, rather than estimate expected forfeitures, which resulted in a cumulative effect adjustment of $0.7 million to reduce retained earnings as of October 1, 2017.

Pending Accounting Pronouncements

Derivative Financial Instruments

In August 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-12, "Derivatives and Hedging (Topic 815) Targeted Improvements to Accounting for Hedging Activities", which amends and simplifies existing guidance in order 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.

Income Taxes

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). 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. The guidance is effective for annual reporting periods beginning after December 15, 2017 (our fiscal 2019) 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. We expect to record a net deferred tax asset of approximately $77 million upon adoption, primarily relating to deductible amortization of intangible assets in Ireland. Post adoption, our effective tax rate will no longer include the benefit of this amortization which is reflected in our effective tax rate reconciliation under the current guidance.

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.

Revenue Recognition

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09). ASU 2014-09 supersedes nearly all existing revenue recognition guidance under U.S. GAAP. The FASB has also issued additional standards to provide clarification and implementation guidance on ASU 2014-09.

The core principle of ASU 2014-09 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 ASU 2014-09, it is possible more judgment and estimates may be required within the revenue recognition process than is required under existing 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.

ASU 2014-09 is effective for us in our first quarter of fiscal 2019. Companies may adopt ASU 2014-09 using either the retrospective method, under which each prior reporting period is presented under ASU 2014-09, with the option to elect certain permitted practical expedients, or the modified retrospective method, under which a company adopts ASU 2014-09 from the beginning of the year of initial application with no restatement of comparative periods, with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application, with certain additional required disclosures. We currently expect to adopt ASU 2014-09 using the modified retrospective method.

While we are continuing to assess the impact of the new standard, we currently believe the most significant impact relates to accounting for our subscription arrangements that include term-based on-premise software licenses bundled with support. Under current GAAP, the revenue attributable to these subscription licenses is 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 will be required to recognize as revenue a portion of the subscription fee upon delivery of the software license. We currently expect revenue related to our perpetual licenses and related support contracts, professional services and cloud offerings to remain substantially unchanged. 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 expect to make 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 contracts entered into or renewed after October 1, 2018. This change will result in annual contractual periods for the majority of our software subscriptions, the license portion of which will be recognized at the beginning of each annual contract period upon delivery of the licenses 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 the current accounting rules.

Under the modified retrospective method, we will evaluate each contract that is ongoing on the adoption date as if that contract had been accounted for under ASU 2014-09 from contract inception. Some license revenue related to subscription arrangements that would have been recognized in future periods under current GAAP will be recast under ASU 2014-09 as if the revenue had been recognized in prior periods. Under this transition method, we will not adjust historical reported revenue amounts. Instead, the revenue that would have been recognized under this method prior to the adoption date will be an adjustment to retained earnings and will not be recognized as revenue in future periods as previously planned. Because we expect that license revenue associated with subscription contracts will be recognized up front instead of over time under ASU 2014-09, we expect some portion of our deferred revenue to be adjusted to retained earnings upon adoption, which could be a material amount. During the first year of adoption, we will disclose the amount of this retained earnings adjustment and intend to provide supplemental disclosure of how this revenue would have been recognized under the current rules.

Another significant provision under ASU 2014-09 includes the capitalization and amortization of costs associated with obtaining a contract, such as sales commissions. Currently, we expense sales commissions in the period incurred. Under ASU 2014-09, 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. While we are continuing to assess the impact of this provision of ASU 2014-09, we likely will be required to capitalize incremental costs such as commissions and amortize those costs over the period the capitalized assets are expected to contribute to future cash flows.

Furthermore, we have made and will continue to make investments in systems and processes to enable timely and accurate reporting under the new standard. We currently expect that necessary operational and internal control structural changes will be implemented prior to the adoption date.