Summary of significant accounting policies (Policies)	9 Months Ended
Summary of significant accounting policies (Policies)	Sep. 30, 2015
Summary of significant accounting policies
Basis of presentation	Basis of Presentation The accompanying financial information as of September 30, 2015 and for the three and nine months ended September 30, 2015 and 2014 has been prepared by the Company, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States (GAAP) have been condensed or omitted pursuant to such rules and regulations. These interim financial statements should be read in conjunction with the Company’s audited financial statements as of December 31, 2014 and notes thereto included in the 2014 Form 10-K. In the opinion of management, the unaudited financial information as of September 30, 2015 and for the three and nine months ended September 30, 2015 and 2014 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three and nine month periods ended September 30, 2015 are not necessarily indicative of the results to be expected for the year ended December 31, 2015 or for any other interim period or for any other future year.
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Inventories and cost of product revenue	Inventories and cost of product revenue On August 4, 2014, the Company was notified that the European Commission, or EC, granted marketing authorization for Translarna for the treatment of nmDMD in ambulatory patients aged five years and older. The marketing authorization allows the Company to market Translarna in the EEA. The launch in these countries is on a country by country basis. This marketing authorization is subject to annual review and renewal by the European Medicines Agency, or EMA following its reassessment of the risk-benefit balance of the authorization and is further conditioned on the Company’s submission of the final report, including additional efficacy and safety data, from ACT DMD during 2015. In the third quarter of 2015, the EMA approved the annual renewal of the marketing authorization for Translarna. If we fail to satisfy renewal requirements, or if it is determined that the balance of risks and benefits of using Translarna changes materially, the European Commission could, at the EMA’s recommendation, vary, suspend, withdraw or refuse to renew the marketing authorization for Translarna or require additional clinical trials. The Company does not have sufficient history or experience from which to accurately forecast product sales or demand generation. As such, the Company has not capitalized inventory and will not capitalize inventory until the completion of ACT DMD and satisfaction of the EMA conditions or until the Company can reasonably predict future product sales. The costs incurred related to the manufacturing of Translarna have been recorded as research and development expense in the consolidated statements of operations. The Company’s cost of product sales includes royalties and other miscellaneous selling costs, which were not material and therefore were included as a component of research and development costs in the current period presentation. The time period over which this inventory is consumed will depend on a number of factors, including the amount of future Translarna sales, and the ability to utilize inventory prior to its expiration date.
Recently issued accounting standards	Recently issued accounting standards In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers”. ASU 2014-09 will eliminate transaction- and industry-specific revenue recognition guidance under current GAAP and replace it with a principle-based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. In July 2015, the Financial Accounting Standards Board voted to delay the effective date of this standard until the first quarter of 2018. Companies are permitted to early adopt the standard in the first quarter of 2017. Presently, the Company is assessing what effect the adoption of ASU 2014-09 will have on its financial statements and accompanying notes. In August 2014, the FASB issued ASU 2014-15, “Presentation of Financial Statements—Going Concern—Disclosures of Uncertainties about an entity’s Ability to Continue as a Going Concern.” ASU 2014-15 provides new guidance related to management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards and to provide related footnote disclosures. This new guidance is effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The requirements of ASU 2014-15 are not expected to have a significant impact on its financial statements and accompanying notes. In April 2015, the FASB issued an amendment to U.S. GAAP to simplify the balance sheet presentation of the costs for issuing debt. The changes were adopted in ASU No. 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issue Costs”. Public companies will have to apply the amendments for reporting periods that begin after December 15, 2015. This amendment requires adoption by revising the balance sheets for periods prior to the effective date. The Company is currently evaluating the impact of this ASU and does not believe the adoption of this ASU will have a material impact on its financial statements and accompanying notes.
Revenue recognition	Revenue Recognition The Company recognizes revenue when amounts are realized or realizable and earned. Revenue is considered realizable and earned when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred or services have been rendered; (3) the price is fixed or determinable; and (4) collection of the amounts due are reasonably assured. Net Product Sales PTC’s net product sales have consisted solely of sales of Translarna for the treatment of nmDMD in territories outside of the U.S. The Company applies the revenue recognition guidance in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Subtopic 605-15, Revenue Recognition—Products. The Company recognizes revenue from product sales when there is persuasive evidence that an arrangement exists, title to product and associated risk of loss has passed to the customer, the price is fixed or determinable, collectability is reasonably assured and the Company has no further performance obligations. The Company records revenue on sales where Translarna is available either on a commercial basis or through a reimbursed early access program and typically paid for by a government authority or institution. Prior to January 1, 2015, the Company recognized revenue for commercial and reimbursed early access program sales on a cash basis once the product was shipped on behalf of the government authority or institution and payment had been received, if all other revenue recognition criteria were met. Beginning in the first quarter of 2015, the Company is recognizing revenue for Translarna as product is shipped, as the Company has established a pattern of collectability. The Company records revenue net of estimated discounts and rebates. Allowances are recorded as a reduction of revenue at the time revenues from product sales are recognized. Allowances for government rebates and discounts are established at the time of delivery. These allowances are adjusted to reflect known changes in factors that may impact such allowances in the quarter those changes are known. Collaboration and Grant Revenue The terms of these agreements typically include payments to the Company of one or more of the following: nonrefundable, upfront license fees; milestone payments; research funding and royalties on future product sales. In addition, the Company generates service revenue through agreements that generally provide for fees for research and development services and may include additional payments upon achievement of specified events. The Company evaluates all contingent consideration earned, such as a milestone payment, using the criteria as provided by the Financial Accounting Standards Board (FASB), guidance on the milestone method of revenue recognition. At the inception of a collaboration arrangement, the Company evaluates if a milestone payment is substantive. The criteria requires that (1) the Company determines if the milestone is commensurate with either its performance to achieve the milestone or the enhancement of value resulting from our activities to achieve the milestone; (2) the milestone be related to past performance; and (3) the milestone be reasonable relative to all deliverable and payment terms of the collaboration arrangement. If these criteria are met then the contingent milestones can be considered a substantive milestone and will be recognized as revenue in the period that the milestone is achieved. The Company recognizes royalties as earned in accordance with the terms of various research and collaboration agreements. If not substantive, the contingent consideration is allocated to the existing units of accounting based on relative selling price and recognized following the same basis previously established for the associated unit of accounting. The Company recognizes revenue for reimbursements of research and development costs under collaboration agreements as the services are performed. The Company records these reimbursements as revenue and not as a reduction of research and development expenses as the Company has the risks and rewards as the principal in the research and development activities.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.