Basis of Presentation and Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements are unaudited and have been prepared by Vertex Pharmaceuticals Incorporated (“Vertex” or the “Company”) in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The condensed consolidated financial statements reflect the operations of (i) the Company, (ii) its wholly-owned subsidiaries and (iii) consolidated variable interest entities (VIEs). All material intercompany balances and transactions have been eliminated. The Company operates in one segment, pharmaceuticals. As of September 30, 2017, the Company deconsolidated Parion Sciences, Inc. (“Parion”), a VIE the Company had consolidated since 2015. The Company's condensed consolidated statement of operations for the interim period ended September 30, 2018 excludes Parion. Please refer to Note B, “Collaborative Arrangements and Acquisitions,” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 that was filed with the Securities and Exchange Commission (the “SEC”) on February 15, 2018 (the “2017 Annual Report on Form 10-K”) for further information regarding the deconsolidation of Parion. Certain information and footnote disclosures normally included in the Company’s 2017 Annual Report on Form 10-K have been condensed or omitted. These interim financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the financial position and results of operations for the interim periods ended September 30, 2018 and 2017. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full fiscal year. These interim financial statements should be read in conjunction with the audited financial statements for the year ended December 31, 2017, which are contained in the 2017 Annual Report on Form 10-K.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the amounts of revenues and expenses during the reported periods. Significant estimates in these condensed consolidated financial statements have been made in connection with the calculation of revenues, inventories, research and development expenses, stock-based compensation expense, the fair value of intangible assets, goodwill, contingent consideration, noncontrolling interest, the consolidation and deconsolidation of VIEs, leases, the fair value of cash flow hedges, deferred tax asset valuation allowances and the provision for or benefit from income taxes. The Company bases its estimates on historical experience and various other assumptions, including in certain circumstances future projections that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Changes in estimates are reflected in reported results in the period in which they become known.
Recently Adopted Accounting Standards	ASC 606 did not have an aggregate impact on the Company’s net cash provided by operating activities, but resulted in offsetting changes in certain assets and liabilities presented within net cash provided by operating activities in the Company’s condensed consolidated statement of cash flows. Equity Investments In 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), which amended guidance related to the recording of financial assets and financial liabilities. Under the amended guidance, equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of an investee) are measured at fair value with changes in fair value recognized in net income (loss). However, an entity has the option to measure equity investments without readily determinable fair values at (i) fair value or (ii) cost adjusted for changes in observable prices minus impairment. Changes in measurement under either alternative are recognized in net income (loss). The amended guidance became effective January 1, 2018 and required the modified-retrospective adoption approach. As of January 1, 2018, the Company held publicly traded equity investments and equity investments accounted for under the cost method. As a result, in the first quarter of 2018, the Company recorded a $25.1 million cumulative effect adjustment to “Accumulated deficit” related to its publicly traded equity investments equal to the unrealized gain, net of tax, that was recorded in “Accumulated other comprehensive income (loss)” as of December 31, 2017. The adoption of ASU 2016-01 had no effect on the Company’s equity investments accounted for under the cost method because the original cost basis of these investments was recorded on the Company’s condensed consolidated balance sheet as of December 31, 2017. In the three and nine months ended September 30, 2018, the Company recorded expense of $61.2 million and income of $88.2 million, respectively, to “Other (expense) income, net,” in its condensed consolidated statement of operations related to the change in fair value of its equity investments. Stock-Based Compensation In 2017, the FASB issued ASU 2017-09, Compensation — Stock Compensation (Topic 718) (“ASU 2017-09”) related to the scope of stock option modification accounting to reduce diversity in practice and provide clarity regarding existing guidance. The new accounting guidance was effective January 1, 2018. The Company does not expect the adoption of ASU 2017-09 to have a significant effect on its condensed consolidated financial statements in future periods and had no effect in the three and nine months ended September 30, 2018. Goodwill In 2017, the FASB issued ASU 2017-04, Intangibles — Goodwill and Other (Topic 350) (“ASU 2017-04”) related to measurements of goodwill. The amended guidance modifies the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value, which eliminates Step 2 from the goodwill impairment test. An entity would recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to the related reporting unit. The new accounting guidance is required for annual or interim goodwill impairment tests conducted after January 1, 2020. The Company early adopted this new guidance and will utilize this approach for annual and interim goodwill impairment tests conducted after January 1, 2018. The Company does not expect the adoption of this guidance to have a significant effect on its condensed consolidated financial statements. Intra-Entity Transfers In 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”), which removes the previous exception in GAAP prohibiting an entity from recognizing current and deferred income tax expenses or benefits related to the transfer of assets, other than inventory, within the consolidated entity. The exception to defer the recognition of any tax impact on the transfer of inventory within the consolidated entity until it is sold to a third party remains unaffected. The amended guidance became effective January 1, 2018. In the first quarter of 2018, upon adoption of ASU 2016-16, the Company recorded a deferred tax asset and corresponding full valuation allowance of $204.7 million equal to the unamortized cost of intellectual property rights transferred to the United Kingdom in 2014 multiplied by an appropriate statutory rate. There was no cumulative effect adjustment to “Accumulated deficit” using the modified-retrospective adoption approach. Cash Flows - Restricted Cash In 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) Restricted Cash (“ASU 2016-18”), which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and restricted cash. Therefore, amounts described as restricted cash should be included with cash and cash equivalents when reconciling the beginning of period and end of period amounts shown on the statement of cash flows. The amended guidance became effective January 1, 2018 and is effective on a retrospective basis. Recently Adopted Accounting Standards Revenue Recognition In 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenues from Contracts with Customers (Topic 606) (“ASC 606”). The new guidance became effective January 1, 2018. ASC 606 applies a more principles-based approach to recognizing revenue. Under ASC 606, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration that an entity expects to receive in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The Company adopted ASC 606 on January 1, 2018 using the modified-retrospective adoption method for all contracts that were not completed as of the date of adoption. Under the modified-retrospective method, the Company recognized the cumulative effect of applying the standard within “Accumulated deficit” on its condensed consolidated balance sheet as of January 1, 2018. For all reporting periods, the Company has not disclosed the value of unsatisfied performance obligations for all product revenue contracts with an original expected length of one year or less, which is an optional exemption that is permitted under the adoption rules. Based on the Company’s review of existing customer contracts as of January 1, 2018, it concluded that the only significant impact that the adoption of ASC 606 had on its financial statements relates to shipments of ORKAMBI under early access programs in France. Prior to the adoption of ASC 606, the Company did not recognize revenue on the proceeds received from sales of ORKAMBI under early access programs in France because the price was not fixed or determinable based on the status of ongoing pricing discussions. As of January 1, 2018, the Company recorded a cumulative effect adjustment to its accumulated deficit of $8.3 million related to the adoption of ASC 606, which primarily represented the Company’s estimated amount of consideration it expects to retain related to these shipments that will not be subject to a significant reversal in amounts recognized, net of costs previously deferred related to these shipments. Please refer to Note B, “Revenue Recognition,” for further information. The Company concluded that the remaining $6.9 million that was recorded as deferred revenue as of December 31, 2017 related to the Company’s 2008 sale of its HIV protease inhibitor royalty stream is not subject to ASC 606 because it was initially accounted for pursuant to ASC 470, Debt, which is not under the scope of ASC 606. The Company will continue to recognize the payment received as royalty revenues over the expected life of the collaboration agreement with GlaxoSmithKline plc based on the units-of-revenue method.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Internal-Use Software In 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 (“ASU 2018-15”), which clarifies the accounting for implementation costs in cloud computing arrangements. The new guidance is effective for the Company on January 1, 2020. Early adoption is permitted. The Company currently is evaluating the impact the adoption of ASU 2018-15 will have on its condensed consolidated financial statements. Fair Value Measurement In 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which modifies the disclosure requirements for fair value measurements. The new guidance is effective for the Company on January 1, 2020. Early adoption is permitted. The Company currently is evaluating the impact the adoption of ASU 2018-13 may have on its disclosures. Derivatives and Hedging In 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815) (“ASU 2017-12”), which helps simplify certain aspects of hedge accounting and enables entities to more accurately present their risk management activities in their financial statements. The new guidance is effective for the Company on January 1, 2019. The Company does not expect the adoption of ASU 2017-12 to have a significant effect on its condensed consolidated financial statements. Leases In 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”), which amends a number of aspects of lease accounting and requires entities to recognize on the balance sheet right-of-use assets and liabilities for leases with lease terms of more than 12 months. ASU 2016-02 requires a modified-retrospective adoption approach. The new guidance is effective for the Company on January 1, 2019. The Company’s project team has reviewed its portfolio of existing leases and current accounting policies to identify and assess the potential differences that would result from applying the requirements of the new standard. The Company anticipates that the amended guidance will result in the recognition of additional right of use assets and corresponding liabilities on its condensed consolidated balance sheets. As discussed in Note K, “Long-term Obligations,” the Company currently applies build-to-suit accounting and is the deemed owner of its leased corporate headquarters in Boston and research site in San Diego, for which it is recognizing depreciation expense over the buildings’ useful lives and imputed interest on the corresponding construction financing lease obligations. Under the amended guidance, the Company expects to account for these buildings as financing leases, resulting in increased depreciation expense over the respective lease terms, which are significantly shorter than the buildings’ useful lives. The Company also expects a reduction in its imputed interest expense in the initial years of each financing lease term. The Company is in the process of quantifying the amount of financing and operating leases, corresponding liabilities and the cumulative effect adjustment to “Accumulated deficit” that will be recorded upon adoption of the amended guidance. The Company is also in the process of implementing appropriate changes to its controls to support lease accounting and related disclosures under the new standard. For a discussion of other recent accounting pronouncements please refer to Note A, “Nature of Business and Accounting Policies—Recent Accounting Pronouncements,” in the 2017 Annual Report on Form 10-K.
Marketable and Equity Securities	Marketable and Equity Securities Effective January 1, 2018, the Company measures publicly traded corporate equity investments that have readily available prices at fair value, with changes in fair value recognized in “Other (expense) income, net,” each reporting period. Effective January 1, 2018, the Company records privately issued corporate equity investments that do not have readily determinable fair values at cost, and adjusts for changes in observable prices minus impairment. Each reporting period, the Company adjusts the carrying value of these investments if it observes that additional shares have been issued in an orderly transaction between market participants resulting in a price increase or decrease per share. Additionally, each reporting period the Company reviews these investments for impairment considering all available information to conclude whether an impairment exists. Changes in measurement for all corporate equity investments are recognized in “Other (expense) income, net.”

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.