Vertex Pharmaceuticals (VRTX) 10-Q 1 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 24, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	VERTEX PHARMACEUTICALS INC / MA
Entity Central Index Key	0000875320
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		256,121,360

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Revenues	$ 858,435	$ 640,799
Costs and expenses:
Cost of sales	95,092	71,613
Research and development expenses	339,490	310,553
Sales, general and administrative expenses	147,045	129,808
Restructuring income	0	(76)
Total costs and expenses	581,627	511,898
Income from operations	276,808	128,901
Interest income	15,615	5,789
Interest expense	(14,868)	(16,886)
Other income, net	42,610	96,838
Income before provision for (benefit from) income taxes	320,165	214,642
Provision for (benefit from) income taxes	51,534	(12,659)
Net income	268,631	227,301
Income attributable to noncontrolling interest	0	(17,038)
Net income attributable to Vertex	$ 268,631	$ 210,263
Net income:
Basic (in dollars per share)	$ 1.05	$ 0.83
Diluted (in dollars per share)	$ 1.03	$ 0.81
Shares used in per share calculations:
Basic (in shares)	255,695	253,231
Diluted (in shares)	260,175	258,526
Product revenues, net
Revenues:
Revenues	$ 857,253	$ 637,729
Collaborative and royalty revenues
Revenues:
Revenues	$ 1,182	$ 3,070

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net income	$ 268,631	$ 227,301
Changes in other comprehensive income (loss):
Unrealized holding gains (losses) on marketable securities, net	596	(460)
Unrealized losses on foreign currency forward contracts, net of tax of $1.5 million and $0.3 million, respectively		(862)
Unrealized losses on foreign currency forward contracts, net of tax of $1.5 million and $0.3 million, respectively	(222)
Foreign currency translation adjustment	4,967	(2,729)
Total changes in other comprehensive income (loss)	5,341	(4,051)
Comprehensive income	273,972	223,250
Comprehensive income attributable to noncontrolling interest	0	(17,038)
Comprehensive income attributable to Vertex	$ 273,972	$ 206,212

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Unrealized losses on foreign currency forward contracts, net of tax	$ 1.5	$ 0.3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 2,893,885	$ 2,650,134
Marketable securities	584,150	518,108
Accounts receivable, net	438,297	409,688
Inventories	136,698	124,360
Prepaid expenses and other current assets	130,009	140,819
Total current assets	4,183,039	3,843,109
Property and equipment, net	742,559	812,005
Goodwill	50,384	50,384
Deferred tax assets	1,467,518	1,499,672
Operating lease assets	60,573
Other assets	39,041	40,728
Total assets	6,543,114	6,245,898
Current liabilities:
Accounts payable	82,262	110,987
Accrued expenses	532,745	604,495
Early access sales accrual	382,703	354,404
Other current liabilities	108,758
Other current liabilities		50,406
Total current liabilities	1,106,468	1,120,292
Long-term finance lease liabilities	560,381
Long-term finance lease liabilities		581,550
Long-term operating lease liabilities	63,484
Long-term advance from collaborator	83,471	82,573
Other long-term liabilities	5,997	26,280
Total liabilities	1,819,801	1,810,695
Commitments and contingencies	0	0
Shareholders’ equity:
Preferred stock, $0.01 par value; 1,000 shares authorized; none issued and outstanding	0	0
Common stock, $0.01 par value; 500,000 shares authorized, 256,351 and 255,172 shares issued and outstanding, respectively	2,561	2,546
Additional paid-in capital	7,475,909	7,421,476
Accumulated other comprehensive income	6,000	659
Accumulated deficit	(2,761,157)	(2,989,478)
Total shareholders’ equity	4,723,313	4,435,203
Total liabilities and shareholders’ equity	$ 6,543,114	$ 6,245,898

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	256,351,000	255,172,000
Common stock, shares outstanding	256,351,000	255,172,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity and Noncontrolling Interest - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Total Vertex Shareholders’ Equity	Noncontrolling Interest
Balance (shares) at Dec. 31, 2017		253,253
Beginning Balance at Dec. 31, 2017	$ 2,042,306	$ 2,512	$ 7,157,362	$ (11,572)	$ (5,119,723)	$ 2,028,579	$ 13,727
Increase (Decrease) in Stockholders' Equity
Other comprehensive loss, net of tax	(4,051)			(4,051)		(4,051)
Net income	227,301				210,263	210,263	17,038
Repurchases of common stock (shares)		(67)
Repurchases of common stock	(11,251)	$ (1)	(11,250)			(11,251)
Issuance of common stock under benefit plans (shares)		1,682
Issuance of common stock under benefit plans	89,686	$ 30	89,656			89,686
Stock-based compensation expense	78,601		78,601			78,601
Other VIE activity	(1,000)						(1,000)
Balance (shares) at Mar. 31, 2018		254,868
Ending Balance at Mar. 31, 2018	2,430,821	$ 2,541	7,314,369	(39,743)	(4,876,111)	2,401,056	29,765
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment for adoption of new accounting guidance	9,229			(24,120)	33,349	9,229
Cumulative effect adjustment for adoption of new accounting guidance	(40,310)				(40,310)	(40,310)
Balance (shares) at Dec. 31, 2018		255,172
Beginning Balance at Dec. 31, 2018	4,435,203	$ 2,546	7,421,476	659	(2,989,478)	4,435,203	0
Increase (Decrease) in Stockholders' Equity
Other comprehensive loss, net of tax	5,341			5,341		5,341
Net income	268,631				268,631	268,631
Repurchases of common stock (shares)		(564)
Repurchases of common stock	(103,839)	$ (6)	(103,833)			(103,839)
Issuance of common stock under benefit plans (shares)		1,743
Issuance of common stock under benefit plans	64,044	$ 21	64,023			64,044
Stock-based compensation expense	94,243		94,243			$ 94,243
Balance (shares) at Mar. 31, 2019		256,351
Ending Balance at Mar. 31, 2019	$ 4,723,313	$ 2,561	$ 7,475,909	$ 6,000	$ (2,761,157)		$ 0

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 268,631	$ 227,301
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	93,791	78,136
Depreciation expense	27,140	16,343
Write-downs of inventories to net realizable value	1,270	3,619
Deferred income taxes	43,425	3,587
Unrealized gain on equity securities	(43,551)	(95,458)
Other non-cash items, net	(3,701)	5,827
Changes in operating assets and liabilities:
Accounts receivable, net	(30,136)	(13,473)
Inventories	(13,139)	(8,208)
Prepaid expenses and other assets	7,941	25,482
Accounts payable	(24,145)	2,154
Accrued expenses and other liabilities	(38,425)	(31,469)
Early access sales accrual	35,683	38,816
Net cash provided by operating activities	324,784	252,657
Cash flows from investing activities:
Purchases of available-for-sale debt securities	(128,215)	(38,653)
Maturities of available-for-sale debt securities	107,118	94,365
Expenditures for property and equipment	(18,041)	(29,279)
Investment in equity securities	0	(21,500)
Net cash (used in) provided by investing activities	(39,138)	4,933
Cash flows from financing activities:
Issuances of common stock under benefit plans	63,620	88,403
Repurchase of common stock	(99,839)	(10,000)
Advance from collaborator	5,000	2,500
Payments on capital lease and construction financing lease obligations		(9,331)
Payments on finance leases	(9,385)
Proceeds related to construction financing lease obligation	0	9,566
Repayments of advanced funding	(1,385)	(1,182)
Other financing activities	0	(1,000)
Net cash (used in) provided by financing activities	(41,989)	78,956
Effect of changes in exchange rates on cash	(378)	1,656
Net increase in cash and cash equivalents	243,279	338,202
Cash, cash equivalents and restricted cash—beginning of period	2,658,253	1,667,526
Cash, cash equivalents and restricted cash—end of period	2,901,532	2,005,728
Supplemental disclosure of cash flow information:
Cash paid for interest	13,148	16,825
Cash paid for income taxes	1,835	1,897
Capitalization of costs related to construction financing lease obligation	0	3,716
Issuances of common stock from employee benefit plans receivable	510	2,124
Accrued share repurchase liability	$ 4,000	$ 0

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	Basis of Presentation and Accounting Policies 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 the Company and its wholly-owned subsidiaries. The Company's condensed consolidated financial statements for the interim period ended March 31, 2018 also include the financial results of BioAxone Biosciences, Inc. (“BioAxone”), a variable interest entity (“VIE”) that the Company consolidated from 2014 through December 31, 2018 . All material intercompany balances and transactions have been eliminated. The Company operates in one segment, pharmaceuticals. The Company has reclassified certain items from the prior year’s condensed consolidated financial statements to conform to the current year’s presentation. Certain information and footnote disclosures normally included in the Company’s 2018 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 March 31, 2019 and 2018 . 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, 2018 , which are contained in the 2018 Annual Report on Form 10-K. 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, research and development expenses, goodwill, 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 Leases In 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASC 842”), which amends a number of aspects of lease accounting and requires entities to recognize right-of-use assets and liabilities on the balance sheet. ASC 842 became effective on January 1, 2019. The Company has finalized its review of its portfolio of existing leases and current accounting policies and has concluded that the amended guidance results in the recognition of additional assets and corresponding liabilities on its balance sheets. The Company also has finalized changes to its controls to address the adoption and ongoing lease accounting and related disclosure requirements of the new standard. Until December 31, 2018, the Company applied build-to-suit accounting and was the deemed owner of its leased corporate headquarters in Boston and research site in San Diego, for which it was recognizing depreciation expense over the buildings’ useful lives and imputed interest on the corresponding construction financing lease obligations. Under the amended guidance that became effective January 1, 2019, the Company accounts for these buildings as finance leases, resulting in increased depreciation expense over the respective lease terms of 15-16 years, which are significantly shorter than the buildings’ useful lives of 40 years. The Company also expects a reduction in its imputed interest expense in the initial years of each finance lease term. In 2019, the Company expects an increase in operating expenses of approximately $26 million and a decrease in interest expense of approximately $13 million due to this change. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), which offered a transition option to entities adopting ASC 842. Under ASU 2018-11, entities could elect to apply ASC 842 using a modified-retrospective adoption approach resulting in a cumulative effect adjustment to accumulated deficit at the beginning of the year in which the new lease standard is adopted, rather than adjustments to the earliest comparative period presented in their financial statements. The Company adopted ASC 842 using the modified-retrospective method. As of January 1, 2019, the Company recorded a cumulative effect adjustment to increase its “ Accumulated deficit ” by $40.3 million related to the adjustments to its build-to-suit leases described in the previous paragraph. The Company elected the package of transition practical expedients for leases that commenced prior to January 1, 2019, allowing it not to reassess (i) whether any expired or existing contracts contain leases, (ii) the lease classification for any expired or existing leases and (iii) the initial indirect costs for any existing leases. Additionally, the Company recorded, upon adoption of ASC 842 on January 1, 2019, operating lease assets of $61.7 million and corresponding liabilities of $71.9 million related to its real estate leases that are not treated as finance leases under ASC 842. The difference between these assets and liabilities is primarily attributable to prepaid or accrued lease payments. The Company also reclassified amounts that were recorded as “Capital lease obligations, current portion” and “Capital lease obligations, excluding current portion” as of December 31, 2018 to “ Other current liabilities ” and “ Long-term finance lease liabilities ,” respectively, on January 1, 2019. These adjustments had no impact on the Company’s condensed consolidated statement of operations and had no impact on the Company’s accumulated deficit. The cumulative effect of applying ASC 842 on the Company’s condensed consolidated balance sheet as of January 1, 2019 was as follows: Balance as of Balance as of December 31, 2018 ^ Adjustments January 1, 2019 Assets (in thousands) Prepaid expenses and other current assets $ 140,819 $ (2,930 ) $ 137,889 Property and equipment, net 812,005 (53,920 ) 758,085 Deferred tax assets 1,499,672 11,236 1,510,908 Operating lease assets — 61,674 61,674 Total assets $ 6,245,898 $ 16,060 $ 6,261,958 Liabilities and Shareholders’ Equity Capital lease obligations, current portion $ 9,817 $ (9,817 ) $ — Other current liabilities 40,589 34,304 74,893 Capital lease obligations, excluding current portion 19,658 (19,658 ) — Construction financing lease obligation, excluding current portion 561,892 (561,892 ) — Long-term finance lease liabilities — 569,487 569,487 Long-term operating lease liabilities — 64,849 64,849 Other long-term liabilities 26,280 (20,903 ) 5,377 Accumulated deficit (2,989,478 ) (40,310 ) (3,029,788 ) Total liabilities and shareholders’ equity $ 6,245,898 $ 16,060 $ 6,261,958 ^ As reported in the Company’s 2018 Annual Report on Form 10-K. Please refer to Note K, “Leases,” for further information regarding the Company’s leases as well as certain disclosures required by ASC 842. 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. ASU 2017-12 became effective January 1, 2019. The adoption of ASU 2017-12 did not have a significant effect on the Company’s condensed consolidated financial statements. 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. ASU 2018-15 is effective on January 1, 2020. Early adoption is permitted. The Company currently is evaluating the impact the adoption of ASU 2018-15 may 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. ASU 2018-13 is effective 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. For a discussion of other recent accounting pronouncements please refer to Note A, “Nature of Business and Accounting Policies—Recent Accounting Pronouncements,” in the 2018 Annual Report on Form 10-K. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note A, “Nature of Business and Accounting Policies,” in its 2018 Annual Report on Form 10-K. The Company is disclosing changes in its accounting policies related to guidance that became effective January 1, 2019 in this Quarterly Report on Form 10-Q. Specifically, the Company has included its policy pursuant to its adoption of ASC 842 below. Leases At the inception of an arrangement, the Company determines whether the arrangement contains a lease. If a lease is identified in an arrangement, the Company recognizes a right-of-use asset and liability on its balance sheet and determines whether the lease should be classified as a finance or operating lease. The Company does not recognize assets or liabilities for leases with lease terms of less than 12 months. A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases. Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes its incremental borrowing rate at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease. The Company does not separate lease and non-lease components when determining which lease payments to include in the calculation of its lease assets and liabilities. Variable lease payments are expensed as incurred. If a lease includes an option to extend or terminate the lease, the Company reflects the option in the lease term if it is reasonably certain it will exercise the option. Finance leases are recorded in “ Property and equipment, net ,” “ Other current liabilities ” and “ Long-term finance lease liabilities ” on the Company’s condensed consolidated balance sheet. Operating leases are recorded in “ Operating lease assets ,” “ Other current liabilities ” and “ Long-term operating lease liabilities ” on the Company’s condensed consolidated balance sheet.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Disaggregation of Revenue Revenues by Product Product revenues, net consisted of the following: Three Months Ended March 31, 2019 2018 (in thousands) SYMDEKO/SYMKEVI $ 320,275 $ 34,124 ORKAMBI 293,007 354,066 KALYDECO 243,971 249,539 Total product revenues, net $ 857,253 $ 637,729 Revenues by Geographic Location Net product revenues are attributed to countries based on the location of the customer. Collaborative and royalty revenues are attributed to countries based on the location of the Company’s subsidiary associated with the collaborative arrangement related to such revenues. Total revenues from external customers and collaborators by geographic region consisted of the following: Three Months Ended March 31, 2019 2018 (in thousands) United States $ 641,104 $ 482,667 Outside of the United States Europe 167,751 131,895 Other 49,580 26,237 Total revenues outside of the United States 217,331 158,132 Total revenues $ 858,435 $ 640,799 In the three months ended March 31, 2019 and 2018 , revenues attributable to Germany contributed the largest amount to the Company’s European revenues. French Early Access Programs In 2015, the Company began distributing ORKAMBI through early access programs in France and continues to be engaged in ongoing pricing discussions regarding the final price for ORKAMBI in France. The Company expects that the difference between the amounts it has collected to date based on the invoiced price and the final negotiated price for ORKAMBI in France will be returned to the French government. Pursuant to the revenue recognition accounting guidance that was applicable until December 31, 2017, the Company’s ORKAMBI net product revenues for 2015, 2016 and 2017 did not include any net product revenues from sales of ORKAMBI in France because the price was not fixed and determinable at the time of delivery. Upon adopting ASU 2014-09, Revenues from Contracts with Customers (Topic 606) , in the first quarter of 2018, the Company began recognizing net product revenues on a portion of its current period sales based on its estimate of consideration it expects to retain that will not be subject to a significant reversal in amounts recognized. If the Company’s estimate regarding the amounts it will receive for ORKAMBI supplied pursuant to these early access programs changes, the Company will reflect the effect of the change in estimate in “ Product revenues, net ” in the period in which the change in estimate occurs. As of March 31, 2019 and December 31, 2018 , the Company’s condensed consolidated balance sheets included an “ Early access sales accrual ” of $382.7 million and $354.4 million , respectively, which was primarily related to the amount it may be required to return to the French government related to ORKAMBI early access programs, which is considered to be a refund liability. Contract Liabilities The Company recorded contract liabilities of $51.4 million and $24.9 million as of March 31, 2019 and December 31, 2018 , respectively, related to annual contracts with government-owned and supported customers in international markets that limit the amount of annual reimbursement the Company can receive. Upon exceeding the annual reimbursement amount, products are provided free of charge, which is a material right. These contracts, which are classified as “ Other current liabilities ,” include upfront payments and fees. The Company defers a portion of the consideration received for shipments made up to the annual reimbursement limit, and the deferred amount is recognized as revenue when the free products are shipped. The Company’s product revenue contracts include performance obligations that are one year or less. Several of the Company’s contract liabilities relate to contracts with annual reimbursement limits in international markets in which the annual period associated with the contract is not the same as the Company’s fiscal year. In the majority of international markets in which the Company has a contract with an annual reimbursement limit, the annual period associated with the contract is the same as the Company’s fiscal year, resulting in no contract liability balance at the end of the year and no revenues recognized in the current year related to performance obligations satisfied in previous years. For the international markets in which the periods associated with these annual contracts are not the same as the Company’s fiscal year, the Company recognizes revenues related to performance obligations satisfied in previous years; however, these amounts are not material to the Company’s financial statements and do not relate to any performance obligations that were satisfied more than 12 months prior to the beginning of the current year.

Collaborative Arrangements and

Collaborative Arrangements and Acquisitions	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Arrangements and Acquisitions	Collaborative Arrangements and Acquisitions The Company has entered into numerous agreements pursuant to which it collaborates with third parties on research, development and commercialization programs, including in-license and out-license agreements and asset acquisitions. In-license Agreements The Company has entered into a number of license agreements in order to advance and obtain access to technologies and services related to its research and early-development activities. The Company is generally required to make an upfront payment upon execution of the license agreement; development, regulatory and commercialization milestones payments upon the achievement of certain product research, development and commercialization objectives; and royalty payments on future sales, if any, of commercial products resulting from the collaboration. Pursuant to the terms of its in-license agreements, the Company’s collaborators lead the discovery efforts and the Company leads all preclinical, development and commercialization activities associated with the advancement of any drug candidates and funds all expenses unless otherwise described below. The Company typically can terminate its in-license agreements by providing advance notice to its collaborators; the required length of notice is dependent on whether any product developed under the license agreement has received marketing approval. The Company’s license agreements may be terminated by either party for a material breach by the other, subject to notice and cure provisions. Unless earlier terminated, these license agreements generally remain in effect until the date on which the royalty term and all payment obligations with respect to all products in all countries have expired. CRISPR Therapeutics AG In 2015, the Company entered into a strategic collaboration, option and license agreement (the “CRISPR Agreement”) with CRISPR Therapeutics AG and its affiliates (“CRISPR”) to collaborate on the discovery and development of potential new treatments aimed at the underlying genetic causes of human diseases using CRISPR-Cas9 gene-editing technology. The Company has the exclusive right to license up to six CRISPR-Cas9-based targets, including targets for the potential treatment of sickle cell disease. In connection with the CRISPR Agreement, the Company made an upfront payment to CRISPR of $75.0 million and an investment in CRISPR’s stock. The Company has also made several subsequent investments in CRISPR’s common stock, which has resulted in CRISPR becoming a related party of the Company. Please refer to Note F, “Marketable Securities and Equity Investments,” for further information regarding the Company’s investment in CRISPR’s common stock. The Company funds all the discovery activities conducted pursuant to the CRISPR Agreement. For targets that the Company elects to license, other than hemoglobinopathy treatments, the Company would lead all development and global commercialization activities. For each target that the Company elects to license, other than hemoglobinopathy targets, CRISPR has the potential to receive up to $420.0 million in development, regulatory and commercial milestones as well as royalties on net product sales. As part of the collaboration, the Company and CRISPR share equally all development costs and potential worldwide revenues related to potential hemoglobinopathy treatments, including treatments for beta thalassemia and sickle cell disease. In 2017, the Company entered into a co-development and co-commercialization agreement with CRISPR pursuant to the terms of the CRISPR Agreement, under which the Company and CRISPR are co-developing and will co-commercialize CTX001 (the “CTX001 Co-Co Agreement”) for the treatment of hemoglobinopathy, including treatments for sickle cell disease and beta thalassemia. The Company concluded that the CTX001 Co-Co Agreement is a cost-sharing arrangement, which results in the net impact of the arrangement being recorded in “ Research and development expenses ” in its condensed consolidated statements of operations. During the three months ended March 31, 2019 and 2018 , the net expense related to the CTX001 Co-Co Agreement was $7.0 million and $3.6 million , respectively. Other In-license Agreements In 2016, the Company entered into a strategic collaboration and licensing agreement with Moderna Therapeutics, Inc. (“Moderna”), pursuant to which the parties are seeking to identify and develop messenger ribonucleic acid, or mRNA, therapeutics for the treatment of CF. The Company made an upfront payment to Moderna of $20.0 million and an investment in Moderna’s preferred stock, which converted to common stock when Moderna became a publicly traded company in December 2018. Moderna has the potential to receive future development and regulatory milestones of up to $275.0 million , as well as royalties on net product sales. Please refer to Note F, “Marketable Securities and Equity Investments,” for further information regarding the Company’s investment in Moderna’s common stock. In December 2018, the Company entered into a strategic collaboration and licensing agreement (the “Arbor Agreement”) with Arbor Biotechnologies, Inc. (“Arbor”) focused on the discovery of novel proteins, including DNA endonucleases, to advance the development of new gene-editing therapies. Pursuant to the Arbor Agreement, Arbor’s platform technology is being applied in the collaboration activities for up to five Vertex disease areas in exchange for an upfront payment of $30.0 million . In addition, the Company received a convertible promissory note that matures in 2023 for an additional $15.0 million payment. For each product identified by the collaboration, Arbor has the potential to receive up to $337.5 million in development, regulatory and commercial milestones as well as royalties on net product sales. The Company determined that the fair value of the convertible promissory note approximated its contractual value upon agreement execution and classifies the convertible note in “ Other assets ” at amortized cost. The Company determined that substantially all of the fair value of the Arbor Agreement was attributable to an in-process research and development asset and no substantive processes were acquired that would constitute a business. The Company concluded that it did not have any alternative future use for the acquired in-process research and development asset and recorded the $30.0 million upfront payment to “ Research and development expenses .” In 2015, the Company entered into a strategic collaboration and license agreement with Parion Sciences, Inc. (“Parion”) focused on the development of investigational epithelial sodium channel (“ENaC”) inhibitors for the potential treatment of CF and all other pulmonary diseases. Parion received a $5.0 million milestone that was recorded as “ Research and development expenses ” in the three months ended March 31, 2019 and has the potential to receive additional development and regulatory milestones related to the ENaC inhibitors. Variable Interest Entities (VIEs) The Company has licensed rights to certain drug candidates from these third-party collaborators, which has resulted in the consolidation of certain third-parties’ financial statements into the Company’s condensed consolidated financial statements as VIEs for certain periods of time. As of December 31, 2018, and continuing through the first quarter of 2019, the Company had no consolidated VIEs reflected in its financial statements. BioAxone Biosciences, Inc. In 2014, the Company entered into a license and collaboration agreement (the “BioAxone Agreement”) with BioAxone, which resulted in the consolidation of BioAxone as a VIE beginning in October 2014. The Company made an initial payment to BioAxone of $10.0 million in 2014. In the three months ended March 31, 2018 , the Company recorded net income attributable to noncontrolling interest of $17.0 million , which was primarily related to a $24.0 million increase in the fair value of the contingent payments payable by Vertex to BioAxone due to (i) the expiration of an option held by the Company to purchase BioAxone in the first quarter of 2018 that increased the probability of a $10.0 million license continuation fee for VX-210 (which was ultimately paid in the first quarter of 2018) and (ii) the probability that additional milestone and royalty payments related to the BioAxone Agreement would be paid. Net income attributable to noncontrolling interest also included a $6.4 million benefit from income taxes during the three months ended March 31, 2018 that was primarily related to the increase in the fair value of the contingent payments. In October 2018, the Company announced it would stop clinical development of VX-210 and terminate the Phase 2b clinical trial of VX-210 based on the recommendation of the clinical trial’s Data Safety Monitoring Board and the Company’s review of interim data from the clinical trial. In December 2018, the Company notified BioAxone of its intent to terminate the BioAxone Agreement and executed a release that immediately allowed BioAxone to control development of its neurological programs other than VX-210 without the Company’s consent. As a result, the Company deconsolidated BioAxone as of December 31, 2018 because it determined that it no longer was the primary beneficiary of BioAxone as it no longer had the power to direct the significant activities of BioAxone. The net impact of the deconsolidation was not material to the Company’s condensed consolidated statement of operations. Asset Acquisition Concert Pharmaceuticals In 2017, the Company acquired certain CF assets including VX-561 (the “Concert Assets”) from Concert Pharmaceuticals Inc. (“Concert”) pursuant to an asset purchase agreement (the “Concert Agreement”). VX-561 is an investigational CFTR potentiator that has the potential to be used as part of combination regimens of CFTR modulators to treat CF. Pursuant to the Concert Agreement, Vertex paid Concert $160.0 million in cash for the Concert Assets, which was recorded to “ Research and development expenses ” in 2017. If VX-561 is approved as part of a combination regimen to treat CF, Concert could receive up to an additional $90.0 million in milestones based on regulatory approval in the United States and reimbursement in the United Kingdom, Germany or France. Out-license agreements The Company has entered into licensing agreements pursuant to which it has out-licensed rights to certain drug candidates to third-party collaborators. Pursuant to these out-license agreements, the Company’s collaborators become responsible for all costs related to the continued development of such drug candidates and obtain development and commercialization rights to these drug candidates. Depending on the terms of the agreements, the Company’s collaborators may be required to make upfront payments, milestone payments upon the achievement of certain product research and development objectives and may also be required to pay royalties on future sales, if any, of commercial products resulting from the collaboration. The termination provisions associated with these collaborations are generally the same as those described above related to the Company’s in-license agreements. Merck KGaA, Darmstadt, Germany In January 2017, the Company entered into a strategic collaboration and license agreement (the “Oncology Agreement”) with Merck KGaA, Darmstadt, Germany (the “Licensee”). Pursuant to the Oncology Agreement, the Company granted the Licensee an exclusive worldwide license to research, develop and commercialize four oncology research and development programs including two clinical-stage programs targeting DNA damage repair: its ataxia telangiectasia and Rad3-related protein kinase inhibitor program, or ATR program, including VX-970 and VX-803, and its DNA-dependent protein kinase inhibitor program, or DNA-PK program, including VX-984. In addition, the Company granted the Licensee exclusive, worldwide rights to two pre-clinical programs. The Company recorded the $230.0 million upfront payment related to the Oncology Agreement as “ Collaborative and royalty revenues ” upon delivery of the license in 2017. The Company’s activities related to the Oncology Agreement were substantially complete in 2017. In December 2018, the Company entered into an agreement with Merck KGaA, Darmstadt, Germany (the “DNA-PK Agreement”) whereby the Company licensed the two lead Vertex DNA-PK compounds from its DNA-PK program for use in the field of gene integration for six specific indications. In exchange for this exclusive worldwide license to research, develop and commercialize the DNA-PK program for the specified indications within the field of gene integration, the Company made an upfront payment of $65.0 million . Merck KGaA, Darmstadt, Germany has the potential to receive additional milestones, primarily related to approval and reimbursement in various markets, as well as royalties on net product sales. The Company evaluated the DNA-PK Agreement and concluded it represents a modification of the Oncology Agreement pursuant to ASC 606. As of December 2018, when the Company entered into the DNA-PK Agreement, the Company had completed its obligations under the Oncology Agreement, but the Oncology Agreement was an open contract pursuant to ASC 606 since the Company could receive future royalty payments from the commercialization of the licensed programs under the Oncology Agreement. In applying ASC 606, the Company determined that the license granted under the DNA-PK Agreement is distinct from the license granted by the Company under the Oncology Agreement since the license to the two lead Vertex DNA-PK compounds is capable of being distinct as the Company is able to benefit from the license via its ability to internally develop and commercialize the two lead Vertex DNA-PK compounds in the six named indications in the field of gene-editing, and the license is not dependent on Merck KGaA, Darmstadt, Germany providing any specialized services to the Company. In addition, the license to the two lead Vertex DNA-PK compounds granted to the Company under the DNA-PK Agreement is distinct from the license granted by the Company under the Oncology Agreement as the rights conveyed in the licenses differ and both parties have the ability to commercially benefit from the licenses on their own. Furthermore, the consideration attributable to the license of the two lead Vertex DNA-PK compounds represents fair value. Therefore, the Company determined it should account for the DNA-PK Agreement as a separate agreement. The Company determined that substantially all of the fair value of the DNA-PK Agreement was attributable to a single in-process research and development asset that did not constitute a business. The Company concluded that it did not have any alternative future use for the acquired in-process research and development asset and recorded the $65.0 million payment to “ Research and development expenses ” accordingly. Janssen Pharmaceuticals, Inc. In 2014, the Company entered into an agreement with Janssen Pharmaceuticals, Inc. (“Janssen”). Pursuant to the agreement, Janssen has an exclusive worldwide license to develop and commercialize certain drug candidates for the treatment of influenza, including pimodivir. The Company has received upfront and milestone payments of $60.0 million from Janssen to date. The most recent milestone was earned based on Janssen’s initiation of a Phase 3 clinical trial in 2017. Cystic Fibrosis Foundation The Company has a research, development and commercialization agreement that was originally entered into in 2004 with Cystic Fibrosis Foundation (“CFF”), as successor in interest to the Cystic Fibrosis Foundation Therapeutics, Inc. This agreement was most recently amended in 2016 (the “2016 Amendment”). Pursuant to the agreement, as amended, the Company agreed to pay royalties ranging from low-single digits to mid-single digits on potential sales of certain compounds first synthesized and/or tested between March 1, 2014 and August 31, 2016, including VX-659 and VX-445, and tiered royalties ranging from single digits to sub-teens on any approved drugs first synthesized and/or tested during a research term on or before February 28, 2014, including KALYDECO (ivacaftor), ORKAMBI (lumacaftor in combination with ivacaftor) and SYMDEKO/SYMKEVI (tezacaftor in combination with ivacaftor). For combination products, such as ORKAMBI and SYMDEKO, sales are allocated equally to each of the active pharmaceutical ingredients in the combination product. There are no remaining commercial milestone payments payable by the Company to CFF pursuant to the agreement. Pursuant to the 2016 Amendment, the Company received an upfront payment of $75.0 million and is receiving development funding from CFF of up to $6.0 million annually. The Company concluded that the upfront payment plus any future development funding represent a form of financing pursuant to ASC 730 and thus records the amounts as a liability on the condensed consolidated balance sheet, primarily reflected in “ Long-term advance from collaborator .” The Company reduces this liability over the estimated royalty term of the agreement and reflects the reductions as an offset to “ Cost of sales ” and as “ Interest expense .” The Company has royalty obligations to CFF for ivacaftor, lumacaftor and tezacaftor until the expiration of patents covering those compounds. The Company has patents in the United States and European Union covering the composition-of-matter of ivacaftor that expire in 2027 and 2025, respectively, subject to potential patent extension. The Company has patents in the United States and European Union covering the composition-of-matter of lumacaftor that expire in 2030 and 2026, respectively, subject to potential extension. The Company has patents in the United States and European Union covering the composition-of-matter of tezacaftor that expire in 2027 and 2028, respectively, subject to potential extension.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic net income per share attributable to Vertex common shareholders is based upon the weighted-average number of common shares outstanding during the period, excluding restricted stock, restricted stock units and performance-based restricted stock units, or “PSUs,” that have been issued but are not yet vested. Diluted net income per share attributable to Vertex common shareholders is based upon the weighted-average number of common shares outstanding during the period plus additional weighted-average common equivalent shares outstanding during the period when the effect is dilutive. The following table sets forth the computation of basic and diluted net income per share for the periods ended: Three Months Ended March 31, 2019 2018 (in thousands, except per share amounts) Basic net income attributable to Vertex per common share calculation: Net income attributable to Vertex common shareholders $ 268,631 $ 210,263 Less: Undistributed earnings allocated to participating securities — (99 ) Net income attributable to Vertex common shareholders—basic $ 268,631 $ 210,164 Basic weighted-average common shares outstanding 255,695 253,231 Basic net income attributable to Vertex per common share $ 1.05 $ 0.83 Diluted net income attributable to Vertex per common share calculation: Net income attributable to Vertex common shareholders $ 268,631 $ 210,263 Less: Undistributed earnings allocated to participating securities — (97 ) Net income attributable to Vertex common shareholders—diluted $ 268,631 $ 210,166 Weighted-average shares used to compute basic net income per common share 255,695 253,231 Effect of potentially dilutive securities: Stock options 2,585 3,248 Restricted stock and restricted stock units (including PSUs) 1,870 2,013 Employee stock purchase program 25 34 Weighted-average shares used to compute diluted net income per common share 260,175 258,526 Diluted net income attributable to Vertex per common share $ 1.03 $ 0.81 The Company did not include the securities in the following table in the computation of the net income per share attributable to Vertex common shareholders calculations because the effect would have been anti-dilutive during each period: Three Months Ended March 31, 2019 2018 (in thousands) Stock options 2,837 1,633 Unvested restricted stock and restricted stock units (including PSUs) 6 4

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The fair value of the Company’s financial assets and liabilities reflects the Company’s estimate of amounts that it would have received in connection with the sale of the assets or paid in connection with the transfer of the liabilities in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of its assets and liabilities, the Company seeks to maximize the use of observable inputs (market data obtained from sources independent from the Company) and to minimize the use of unobservable inputs (the Company’s assumptions about how market participants would price assets and liabilities). The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities: Level 1: Quoted prices in active markets for identical assets or liabilities. An active market for an asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2: Observable inputs other than Level 1 inputs. Examples of Level 2 inputs include quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active. Level 3: Unobservable inputs based on the Company’s assessment of the assumptions that market participants would use in pricing the asset or liability. The Company’s investment strategy is focused on capital preservation. The Company invests in instruments that meet the credit quality standards outlined in the Company’s investment policy. This policy also limits the amount of credit exposure to any one issue or type of instrument. The Company maintains strategic investments separately from the investment policy that governs its other cash, cash equivalents and marketable securities as described in “ Note F, “Marketable Securities and Equity Investments.” As of March 31, 2019 , the Company’s investments were in money market funds, U.S. Treasury securities, government-sponsored enterprise securities, corporate debt securities, commercial paper and corporate equity securities. Additionally, the Company utilizes foreign currency forward contracts intended to mitigate the effect of changes in foreign exchange rates on its condensed consolidated statement of operations. As of March 31, 2019 , all of the Company’s financial assets and liabilities that were subject to fair value measurements were valued using observable inputs. The Company’s financial assets valued based on Level 1 inputs consisted of money market funds, U.S. Treasury securities, government-sponsored enterprise securities and corporate equity securities. The Company’s financial assets and liabilities valued based on Level 2 inputs consisted of certain corporate equity securities as described below, corporate debt securities, commercial paper, which consisted of investments in highly-rated investment-grade corporations, and foreign currency forward contracts with reputable and creditworthy counterparties. In 2018, Moderna became a publicly traded company. The Company has valued its investment in Moderna based on Level 2 inputs due to transfer restrictions subsequent to Moderna’s initial public offering lasting until December 2019. The reduction in fair value recorded on the Company’s condensed consolidated balance sheet related to this transfer restriction is not material to its financial statements. During the three months ended March 31, 2019 and 2018 , the Company did not record any other-than-temporary impairment charges related to its financial assets. The following table sets forth the Company’s financial assets and liabilities subject to fair value measurements (and does not include $1.5 billion and $ 1.4 billion of cash as of March 31, 2019 and December 31, 2018 , respectively): Fair Value Measurements as of March 31, 2019 Fair Value Hierarchy Total Level 1 Level 2 Level 3 (in thousands) Financial instruments carried at fair value (asset positions): Cash equivalents: Money market funds $ 1,354,656 $ 1,354,656 $ — $ — U.S. Treasury securities 5,996 5,996 — — Government-sponsored enterprise securities 11,786 11,786 — — Corporate debt securities 4,519 — 4,519 — Commercial paper 35,955 — 35,955 — Marketable securities: Corporate equity securities 210,874 192,207 18,667 — Government-sponsored enterprise securities 15,181 15,181 — — Corporate debt securities 231,572 — 231,572 — Commercial paper 126,523 — 126,523 — Prepaid expenses and other current assets: Foreign currency forward contracts 19,210 — 19,210 — Other assets: Foreign currency forward contracts 973 — 973 — Total financial assets $ 2,017,245 $ 1,579,826 $ 437,419 $ — Financial instruments carried at fair value (liability positions): Other current liabilities: Foreign currency forward contracts $ (310 ) $ — $ (310 ) $ — Other long-term liabilities: Foreign currency forward contracts (68 ) — (68 ) — Total financial liabilities $ (378 ) $ — $ (378 ) $ — Fair Value Measurements as of December 31, 2018 Fair Value Hierarchy Total Level 1 Level 2 Level 3 (in thousands) Financial instruments carried at fair value (asset positions): Cash equivalents: Money market funds $ 1,226,603 $ 1,226,603 $ — $ — U.S. Treasury securities 5,966 5,966 — — Government-sponsored enterprise securities 7,123 7,123 — — Commercial paper 58,268 — 58,268 — Marketable securities: Corporate equity securities 167,323 153,733 13,590 — U.S. Treasury securities 6,026 6,026 — — Government-sponsored enterprise securities 10,704 10,704 — — Corporate debt securities 233,665 — 233,665 — Commercial paper 100,390 — 100,390 — Prepaid expenses and other current assets: Foreign currency forward contracts 19,023 — 19,023 — Other assets: Foreign currency forward contracts 1,514 — 1,514 — Total financial assets $ 1,836,605 $ 1,410,155 $ 426,450 $ — Financial instruments carried at fair value (liability positions): Other current liabilities: Foreign currency forward contracts $ (340 ) $ — $ (340 ) $ — Other long-term liabilities: Foreign currency forward contracts (108 ) — (108 ) — Total financial liabilities $ (448 ) $ — $ (448 ) $ — Please refer to Note F, “Marketable Securities and Equity Investments,” for the carrying amount and related unrealized gains (losses) by type of investment.

Marketable Securities and Equit

Marketable Securities and Equity Investments	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Marketable Securities and Equity Investments	Marketable Securities and Equity Investments A summary of the Company’s cash equivalents and marketable securities, which are recorded at fair value (and do not include $1.5 billion and $ 1.4 billion of cash as of March 31, 2019 and December 31, 2018 , respectively), is shown below: Amortized Cost Gross Gross Fair Value (in thousands) As of March 31, 2019 Cash equivalents: Money market funds $ 1,354,656 $ — $ — $ 1,354,656 U.S. Treasury securities 5,996 — — 5,996 Government-sponsored enterprise securities 11,787 — (1 ) 11,786 Corporate debt securities 4,519 — — 4,519 Commercial paper 35,959 — (4 ) 35,955 Total cash equivalents 1,412,917 — (5 ) 1,412,912 Marketable securities: Government-sponsored enterprise securities 15,180 2 (1 ) 15,181 Corporate debt securities 231,516 88 (32 ) 231,572 Commercial paper 126,515 34 (26 ) 126,523 Total marketable debt securities 373,211 124 (59 ) 373,276 Corporate equity securities 133,157 79,093 (1,376 ) 210,874 Total marketable securities $ 506,368 $ 79,217 $ (1,435 ) $ 584,150 As of December 31, 2018 Cash equivalents: Money market funds $ 1,226,603 $ — $ — $ 1,226,603 U.S. Treasury securities 5,967 — (1 ) 5,966 Government-sponsored enterprise securities 7,124 — (1 ) 7,123 Commercial paper 58,271 — (3 ) 58,268 Total cash equivalents 1,297,965 — (5 ) 1,297,960 Marketable securities: U.S. Treasury securities 6,026 — — 6,026 Government-sponsored enterprise securities 10,704 — — 10,704 Corporate debt securities 234,088 27 (450 ) 233,665 Commercial paper 100,498 — (108 ) 100,390 Total marketable debt securities 351,316 27 (558 ) 350,785 Corporate equity securities 133,157 40,619 (6,453 ) 167,323 Total marketable securities $ 484,473 $ 40,646 $ (7,011 ) $ 518,108 Available-for-sale debt securities were recorded in the Company's condensed consolidated balance sheets at fair value as follows: As of March 31, 2019 As of December 31, 2018 (in thousands) Cash and cash equivalents $ 1,412,912 $ 1,297,960 Marketable securities 373,276 350,785 Total $ 1,786,188 $ 1,648,745 Available-for-sale debt securities by contractual maturity were as follows: As of March 31, 2019 As of December 31, 2018 (in thousands) Matures within one year $ 1,775,571 $ 1,647,500 Matures after one year through five years 10,617 1,245 Total $ 1,786,188 $ 1,648,745 The Company has a limited number of available-for-sale debt securities in insignificant loss positions as of March 31, 2019 , which it does not intend to sell and has concluded it will not be required to sell before recovery of the amortized costs for the investments at maturity. The Company did no t record any charges for other-than-temporary declines in the fair value of available-for-sale debt securities or gross realized gains or losses in the three months ended March 31, 2019 and 2018 . The Company maintains strategic investments separately from the investment policy that governs its other cash, cash equivalents and marketable securities. The Company’s investments in the common stock of publicly traded companies, CRISPR and Moderna as of March 31, 2019 and December 31, 2018 , respectively, have readily determinable fair values and are recorded in “ Marketable securities ” on its condensed consolidated balance sheets. As of March 31, 2019 and December 31, 2018 , the total fair value of the Company’s strategic investments in the common stock of publicly traded companies, was $210.9 million and $167.3 million , respectively. During the three months ended March 31, 2019 and 2018 , the Company recorded unrealized gains of $43.6 million and $95.5 million , respectively, primarily related to increases in the fair value of its investment in CRISPR. As of March 31, 2019 , the carrying value of the Company’s equity investments without readily determinable fair values, which are recorded in “ Other assets ” on its condensed consolidated balance sheets, was $13.6 million .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table summarizes the changes in accumulated other comprehensive (loss) income by component: Unrealized Holding Gains (Losses), Net of Tax Foreign Currency Translation Adjustment On Available-For-Sale Debt Securities On Foreign Currency Forward Contracts Total (in thousands) Balance at December 31, 2018 $ (11,227 ) $ (536 ) $ 12,422 $ 659 Other comprehensive income before reclassifications 4,967 596 5,126 10,689 Amounts reclassified from accumulated other comprehensive income — — (5,348 ) (5,348 ) Net current period other comprehensive income (loss) 4,967 596 (222 ) 5,341 Balance at March 31, 2019 $ (6,260 ) $ 60 $ 12,200 $ 6,000 Unrealized Holding Gains (Losses), Net of Tax Foreign Currency Translation Adjustment On Available-For-Sale Debt Securities On Equity Securities On Foreign Currency Forward Contracts Total (in thousands) Balance at December 31, 2017 $ (21,031 ) $ (594 ) $ 25,069 $ (15,016 ) $ (11,572 ) Other comprehensive loss before reclassifications (2,729 ) (460 ) — (7,639 ) (10,828 ) Amounts reclassified from accumulated other comprehensive income (loss) — — — 6,777 6,777 Net current period other comprehensive loss (2,729 ) (460 ) — (862 ) (4,051 ) Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard 949 — (25,069 ) — (24,120 ) Balance at March 31, 2018 $ (22,811 ) $ (1,054 ) $ — $ (15,878 ) $ (39,743 )

Hedging

Hedging	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Hedging	Hedging Foreign currency forward contracts - Designated as hedging instruments The Company maintains a hedging program intended to mitigate the effect of changes in foreign exchange rates for a portion of the Company’s forecasted product revenues denominated in certain foreign currencies. The program includes foreign currency forward contracts that are designated as cash flow hedges under GAAP having contractual durations from one to eighteen months. The Company recognizes realized gains and losses for the effective portion of such contracts in “ Product revenues, net ” in its condensed consolidated statements of operations in the same period that it recognizes the product revenues that were impacted by the hedged foreign exchange rate changes. The Company formally documents the relationship between foreign currency forward contracts (hedging instruments) and forecasted product revenues (hedged items), as well as the Company’s risk management objective and strategy for undertaking various hedging activities, which includes matching all foreign currency forward contracts that are designated as cash flow hedges to forecasted transactions. The Company also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the foreign currency forward contracts are highly effective in offsetting changes in cash flows of hedged items. If the Company were to determine that a (i) foreign currency forward contract is not highly effective as a cash flow hedge, (ii) foreign currency forward contract has ceased to be a highly effective hedge or (iii) forecasted transaction is no longer probable of occurring, the Company would discontinue hedge accounting treatment prospectively. The Company measures effectiveness based on the change in fair value of the forward contracts and the fair value of the hypothetical foreign currency forward contracts with terms that match the critical terms of the risk being hedged. As of March 31, 2019 , all hedges were determined to be highly effective. The Company considers the impact of its counterparties’ credit risk on the fair value of the foreign currency forward contracts. As of March 31, 2019 and December 31, 2018 , credit risk did not change the fair value of the Company’s foreign currency forward contracts. The following table summarizes the notional amount of the Company’s outstanding foreign currency forward contracts designated as cash flow hedges under GAAP: As of March 31, 2019 As of December 31, 2018 Foreign Currency (in thousands) Euro $ 373,264 $ 335,179 British pound sterling 76,685 73,460 Australian dollar 70,889 52,820 Canadian dollar 40,089 43,759 Total foreign currency forward contracts $ 560,927 $ 505,218 Foreign currency forward contracts - Not designated as hedging instruments The Company also enters into foreign currency forward contracts with contractual maturities of less than one month, which are designed to mitigate the effect of changes in foreign exchange rates on monetary assets and liabilities, including intercompany balances. These contracts are not designated as hedging instruments under GAAP. The Company recognizes realized gains and losses for such contracts in “ Other income, net ” in its condensed consolidated statements of operations each period. As of March 31, 2019 , the notional amount of the Company’s outstanding foreign currency forward contracts where hedge accounting under GAAP is not applied was $220.9 million . During the three months ended March 31, 2019 and 2018 , the Company recognized the following related to foreign currency forward contacts in its condensed consolidated statements of operations: Three Months Ended March 31, 2019 2018 (in thousands) Designated as hedging instruments - Reclassified from AOCI Product revenues, net $ 6,839 $ (6,485 ) Not designated as hedging instruments Other income, net $ 3,151 $ 1,539 The following table summarizes the fair value of the Company’s outstanding foreign currency forward contracts designated as cash flow hedges under GAAP included on its condensed consolidated balance sheets: As of March 31, 2019 Assets Liabilities Classification Fair Value Classification Fair Value (in thousands) Prepaid expenses and other current assets $ 19,210 Other current liabilities $ (310 ) Other assets 973 Other long-term liabilities (68 ) Total assets $ 20,183 Total liabilities $ (378 ) As of December 31, 2018 Assets Liabilities Classification Fair Value Classification Fair Value (in thousands) Prepaid expenses and other current assets $ 19,023 Other current liabilities $ (340 ) Other assets 1,514 Other long-term liabilities (108 ) Total assets $ 20,537 Total liabilities $ (448 ) As of March 31, 2019 , the Company expects amounts that are related to foreign exchange forward contracts designated as cash flow hedges under GAAP recorded in “ Prepaid expenses and other current assets ” and “ Other current liabilities ” to be reclassified to earnings within twelve months. The following table summarizes the potential effect of offsetting derivatives by type of financial instrument designated as cash flow hedges under GAAP on the Company’s condensed consolidated balance sheets: As of March 31, 2019 Gross Amounts Recognized Gross Amounts Offset Gross Amounts Presented Gross Amounts Not Offset Legal Offset Foreign currency forward contracts (in thousands) Total assets $ 20,183 $ — $ 20,183 $ (378 ) $ 19,805 Total liabilities $ (378 ) $ — $ (378 ) $ 378 $ — As of December 31, 2018 Gross Amounts Recognized Gross Amounts Offset Gross Amounts Presented Gross Amounts Not Offset Legal Offset Foreign currency forward contracts (in thousands) Total assets $ 20,537 $ — $ 20,537 $ (448 ) $ 20,089 Total liabilities $ (448 ) $ — $ (448 ) $ 448 $ —

Inventories

Inventories	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following: As of March 31, 2019 As of December 31, 2018 (in thousands) Raw materials $ 11,649 $ 9,677 Work-in-process 80,529 87,944 Finished goods 44,520 26,739 Total $ 136,698 $ 124,360

Revolving Credit Facility

Revolving Credit Facility	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Revolving Credit Facility	Revolving Credit Facility In October 2016, the Company entered into a Credit Agreement (the “Credit Agreement”) with Bank of America, N.A., as administrative agent and the lenders referred to therein. The Credit Agreement provides for a $500.0 million revolving facility, $300.0 million of which was drawn at closing (the “Loans”) and was repaid in February 2017. The Credit Agreement also provides that, subject to satisfaction of certain conditions, the Company may request that the borrowing capacity under the Credit Agreement be increased by an additional $300.0 million . The Credit Agreement matures on October 13, 2021. The Loans will bear interest, at the Company’s option, at either a base rate or a Eurodollar rate, in each case plus an applicable margin. Under the Credit Agreement, the applicable margins on base rate loans range from 0.75% to 1.50% and the applicable margins on Eurodollar loans range from 1.75% to 2.50% , in each case based on the Company’s consolidated leverage ratio (the ratio of the Company’s total consolidated debt to the Company’s trailing twelve-month EBITDA). The Loans are guaranteed by certain of the Company’s domestic subsidiaries and secured by substantially all of the Company’s assets and the assets of the Company’s domestic subsidiaries (excluding intellectual property, owned and leased real property and certain other excluded property) and by the equity interests of the Company’s subsidiaries, subject to certain exceptions. Under the terms of the Credit Agreement, the Company must maintain, subject to certain limited exceptions, a consolidated leverage ratio of 3.00 to 1.00 and consolidated EBITDA of at least $200.0 million , in each case measured on a quarterly basis. The Credit Agreement contains customary representations and warranties and usual and customary affirmative and negative covenants. The Credit Agreement also contains customary events of default. In the case of a continuing event of default, the administrative agent would be entitled to exercise various remedies, including the acceleration of amounts due under outstanding loans.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases Finance Leases The Company’s finance lease assets and liabilities primarily relate to its corporate headquarters in Boston and research site in San Diego (the “Buildings”). These Buildings are classified as finance leases because the present value of the sum of the lease payments associated with the Buildings exceeds substantially all of the fair value of the Buildings. The Company also has outstanding finance leases for equipment. Prior to the adoption of ASC 842 on January 1, 2019, the Company was deemed for accounting purposes to be the owner of the Buildings during their construction periods and recorded project construction costs incurred by its landlords. Upon completion of the Buildings, the Company determined that the underlying leases did not meet the criteria for “sale-leaseback” treatment. Accordingly, the Company depreciated the Buildings over 40 years and recorded interest expense associated with the financing obligations for the Buildings. The Company bifurcated the lease payments pursuant to the Buildings into (i) a portion that was allocated to the buildings and (ii) a portion that is allocated to the land on which the buildings were constructed. The portion of the lease obligations allocated to the land was treated as an operating lease. Pursuant to ASC 842, the Company adjusted the amounts recorded on its condensed consolidated balance sheet as of January 1, 2019 for the Buildings to reflect the present value of the lease payments over the remaining lease term related to the Buildings. The finance lease assets associated with the Buildings are amortized to depreciation expense using the straight-line method over the remaining lease term, which is significantly shorter than the Buildings’ useful lives. The Company continues to record interest expense associated with the finance lease liabilities for the Buildings. Corporate Headquarters In 2011, the Company entered into two lease agreements, pursuant to which the Company leases approximately 1.1 million square feet of office and laboratory space in two buildings in Boston, Massachusetts for a term of 15 years. Base rent payments commenced in December 2013, and will continue through December 2028. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease terms for an additional ten years. San Diego Lease In 2015, the Company entered into a lease agreement pursuant to which the Company leases approximately 170,000 square feet of office and laboratory space in San Diego, California for a term of 16 years. Base rent payments will commence in the second quarter of 2019, and will continue through May 2034. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease term for up to two additional five -year terms. The Company placed this building in service in the second quarter of 2018. Operating Leases The Company’s operating leases relate to its real estate leases that are not classified as finance leases. Aggregate Lease Information Related to the Application of ASC 842 The following information is disclosed in accordance with ASC 842, which became effective January 1, 2019. The components of lease cost recorded in the Company’s condensed consolidated statement of operations were as follows: Three Months Ended March 31, 2019 (in thousands) Operating lease cost $ 2,639 Finance lease cost Amortization of leased assets 12,365 Interest on lease liabilities 13,449 Variable lease cost 6,762 Sublease income (1,484 ) Net lease cost $ 33,731 The Company’s variable lease cost during the three months ended March 31, 2019 primarily related to operating expenses, taxes and insurance associated with its finance leases. The Company’s sublease income during the three months ended March 31, 2019 primarily related to subleases for an insignificant portion of the Company’s corporate headquarters. The Company’s leases are included on its condensed consolidated balance sheets as follows: As of March 31, 2019 As of December 31, 2018 ^ (in thousands) Finance leases Property and equipment, net $ 473,129 $ 640,952 Total finance lease assets $ 473,129 $ 640,952 Capital lease obligations, current portion $ — $ 9,817 Other current liabilities 35,725 5,271 Capital lease obligations, excluding current portion — 19,658 Construction financing lease obligation, excluding current portion — 561,892 Long-term finance lease liabilities 560,381 — Total finance lease liabilities $ 596,106 $ 596,638 Operating leases Operating lease assets $ 60,573 $ — Total operating lease assets $ 60,573 $ — Other current liabilities $ 7,520 $ — Long-term operating lease liabilities 63,484 — Total operating lease liabilities $ 71,004 $ — ^ As reported in the Company’s 2018 Annual Report on Form 10-K. Maturities of the Company’s finance and operating lease liabilities in accordance with ASC 842 as of March 31, 2019 were as follows: Year Finance Leases Operating Leases Total (in thousands) Remainder of 2019 $ 61,339 $ 7,331 $ 68,670 2020 88,998 10,366 99,364 2021 87,365 8,658 96,023 2022 85,016 8,233 93,249 2023 84,092 8,151 92,243 Thereafter 512,804 46,212 559,016 Total lease payments 919,614 88,951 1,008,565 Less: amount representing interest (323,508 ) (17,947 ) (341,455 ) Present value of lease liabilities $ 596,106 $ 71,004 $ 667,110 The weighted-average remaining lease terms and discount rates related to the Company’s leases were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (in years) Finance leases 10.45 Operating leases 10.91 Weighted-average discount rate Finance leases 9.11 % Operating leases 4.05 % Please refer to Note O, “Additional Cash Flow Information,” for cash flow impact of the Company’s leases. Additional Lease Information Related to the Application of ASC 840 The following information is disclosed in accordance with ASC 840, Leases (Topic 840) (“ASC 840”), which was applicable until December 31, 2018. As of December 31, 2018, future minimum commitments under the Company’s real estate leases with initial terms of more than one year were as follows: Year Fan Pier San Diego Lease Other Total Lease (in thousands) 2019 $ 66,540 $ 5,324 $ 13,207 $ 85,071 2020 72,589 9,127 14,270 95,986 2021 72,589 9,127 12,529 94,245 2022 72,589 9,127 12,045 93,761 2023 72,589 9,530 11,952 94,071 Thereafter 389,855 119,864 65,472 575,191 Total minimum lease payments $ 746,751 $ 162,099 $ 129,475 $ 1,038,325 As of December 31, 2018, the Company’s total sublease income to be received related to its facility leases was $6.2 million . During the three months ended March 31, 2018 , rental expense was $4.6 million . As of December 31, 2018, the Company had outstanding capital leases totaling gross property and equipment of $94.8 million and accumulated depreciation of $34.0 million . The capital leases, which were related to equipment and leasehold improvements, bore interest at rates ranging from less than 1% to 6% per year. The Company’s capital lease amortization was included in depreciation expense during the three months ended March 31, 2018 . The following table set forth the Company’s future minimum payments due under capital leases as of December 31, 2018: Year (in thousands) 2019 $ 10,770 2020 7,282 2021 5,649 2022 3,300 2023 1,974 Thereafter 3,085 Total payments 32,060 Less: amount representing interest (2,585 ) Present value of payments $ 29,475
Leases	Leases Finance Leases The Company’s finance lease assets and liabilities primarily relate to its corporate headquarters in Boston and research site in San Diego (the “Buildings”). These Buildings are classified as finance leases because the present value of the sum of the lease payments associated with the Buildings exceeds substantially all of the fair value of the Buildings. The Company also has outstanding finance leases for equipment. Prior to the adoption of ASC 842 on January 1, 2019, the Company was deemed for accounting purposes to be the owner of the Buildings during their construction periods and recorded project construction costs incurred by its landlords. Upon completion of the Buildings, the Company determined that the underlying leases did not meet the criteria for “sale-leaseback” treatment. Accordingly, the Company depreciated the Buildings over 40 years and recorded interest expense associated with the financing obligations for the Buildings. The Company bifurcated the lease payments pursuant to the Buildings into (i) a portion that was allocated to the buildings and (ii) a portion that is allocated to the land on which the buildings were constructed. The portion of the lease obligations allocated to the land was treated as an operating lease. Pursuant to ASC 842, the Company adjusted the amounts recorded on its condensed consolidated balance sheet as of January 1, 2019 for the Buildings to reflect the present value of the lease payments over the remaining lease term related to the Buildings. The finance lease assets associated with the Buildings are amortized to depreciation expense using the straight-line method over the remaining lease term, which is significantly shorter than the Buildings’ useful lives. The Company continues to record interest expense associated with the finance lease liabilities for the Buildings. Corporate Headquarters In 2011, the Company entered into two lease agreements, pursuant to which the Company leases approximately 1.1 million square feet of office and laboratory space in two buildings in Boston, Massachusetts for a term of 15 years. Base rent payments commenced in December 2013, and will continue through December 2028. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease terms for an additional ten years. San Diego Lease In 2015, the Company entered into a lease agreement pursuant to which the Company leases approximately 170,000 square feet of office and laboratory space in San Diego, California for a term of 16 years. Base rent payments will commence in the second quarter of 2019, and will continue through May 2034. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease term for up to two additional five -year terms. The Company placed this building in service in the second quarter of 2018. Operating Leases The Company’s operating leases relate to its real estate leases that are not classified as finance leases. Aggregate Lease Information Related to the Application of ASC 842 The following information is disclosed in accordance with ASC 842, which became effective January 1, 2019. The components of lease cost recorded in the Company’s condensed consolidated statement of operations were as follows: Three Months Ended March 31, 2019 (in thousands) Operating lease cost $ 2,639 Finance lease cost Amortization of leased assets 12,365 Interest on lease liabilities 13,449 Variable lease cost 6,762 Sublease income (1,484 ) Net lease cost $ 33,731 The Company’s variable lease cost during the three months ended March 31, 2019 primarily related to operating expenses, taxes and insurance associated with its finance leases. The Company’s sublease income during the three months ended March 31, 2019 primarily related to subleases for an insignificant portion of the Company’s corporate headquarters. The Company’s leases are included on its condensed consolidated balance sheets as follows: As of March 31, 2019 As of December 31, 2018 ^ (in thousands) Finance leases Property and equipment, net $ 473,129 $ 640,952 Total finance lease assets $ 473,129 $ 640,952 Capital lease obligations, current portion $ — $ 9,817 Other current liabilities 35,725 5,271 Capital lease obligations, excluding current portion — 19,658 Construction financing lease obligation, excluding current portion — 561,892 Long-term finance lease liabilities 560,381 — Total finance lease liabilities $ 596,106 $ 596,638 Operating leases Operating lease assets $ 60,573 $ — Total operating lease assets $ 60,573 $ — Other current liabilities $ 7,520 $ — Long-term operating lease liabilities 63,484 — Total operating lease liabilities $ 71,004 $ — ^ As reported in the Company’s 2018 Annual Report on Form 10-K. Maturities of the Company’s finance and operating lease liabilities in accordance with ASC 842 as of March 31, 2019 were as follows: Year Finance Leases Operating Leases Total (in thousands) Remainder of 2019 $ 61,339 $ 7,331 $ 68,670 2020 88,998 10,366 99,364 2021 87,365 8,658 96,023 2022 85,016 8,233 93,249 2023 84,092 8,151 92,243 Thereafter 512,804 46,212 559,016 Total lease payments 919,614 88,951 1,008,565 Less: amount representing interest (323,508 ) (17,947 ) (341,455 ) Present value of lease liabilities $ 596,106 $ 71,004 $ 667,110 The weighted-average remaining lease terms and discount rates related to the Company’s leases were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (in years) Finance leases 10.45 Operating leases 10.91 Weighted-average discount rate Finance leases 9.11 % Operating leases 4.05 % Please refer to Note O, “Additional Cash Flow Information,” for cash flow impact of the Company’s leases. Additional Lease Information Related to the Application of ASC 840 The following information is disclosed in accordance with ASC 840, Leases (Topic 840) (“ASC 840”), which was applicable until December 31, 2018. As of December 31, 2018, future minimum commitments under the Company’s real estate leases with initial terms of more than one year were as follows: Year Fan Pier San Diego Lease Other Total Lease (in thousands) 2019 $ 66,540 $ 5,324 $ 13,207 $ 85,071 2020 72,589 9,127 14,270 95,986 2021 72,589 9,127 12,529 94,245 2022 72,589 9,127 12,045 93,761 2023 72,589 9,530 11,952 94,071 Thereafter 389,855 119,864 65,472 575,191 Total minimum lease payments $ 746,751 $ 162,099 $ 129,475 $ 1,038,325 As of December 31, 2018, the Company’s total sublease income to be received related to its facility leases was $6.2 million . During the three months ended March 31, 2018 , rental expense was $4.6 million . As of December 31, 2018, the Company had outstanding capital leases totaling gross property and equipment of $94.8 million and accumulated depreciation of $34.0 million . The capital leases, which were related to equipment and leasehold improvements, bore interest at rates ranging from less than 1% to 6% per year. The Company’s capital lease amortization was included in depreciation expense during the three months ended March 31, 2018 . The following table set forth the Company’s future minimum payments due under capital leases as of December 31, 2018: Year (in thousands) 2019 $ 10,770 2020 7,282 2021 5,649 2022 3,300 2023 1,974 Thereafter 3,085 Total payments 32,060 Less: amount representing interest (2,585 ) Present value of payments $ 29,475
Leases	Leases Finance Leases The Company’s finance lease assets and liabilities primarily relate to its corporate headquarters in Boston and research site in San Diego (the “Buildings”). These Buildings are classified as finance leases because the present value of the sum of the lease payments associated with the Buildings exceeds substantially all of the fair value of the Buildings. The Company also has outstanding finance leases for equipment. Prior to the adoption of ASC 842 on January 1, 2019, the Company was deemed for accounting purposes to be the owner of the Buildings during their construction periods and recorded project construction costs incurred by its landlords. Upon completion of the Buildings, the Company determined that the underlying leases did not meet the criteria for “sale-leaseback” treatment. Accordingly, the Company depreciated the Buildings over 40 years and recorded interest expense associated with the financing obligations for the Buildings. The Company bifurcated the lease payments pursuant to the Buildings into (i) a portion that was allocated to the buildings and (ii) a portion that is allocated to the land on which the buildings were constructed. The portion of the lease obligations allocated to the land was treated as an operating lease. Pursuant to ASC 842, the Company adjusted the amounts recorded on its condensed consolidated balance sheet as of January 1, 2019 for the Buildings to reflect the present value of the lease payments over the remaining lease term related to the Buildings. The finance lease assets associated with the Buildings are amortized to depreciation expense using the straight-line method over the remaining lease term, which is significantly shorter than the Buildings’ useful lives. The Company continues to record interest expense associated with the finance lease liabilities for the Buildings. Corporate Headquarters In 2011, the Company entered into two lease agreements, pursuant to which the Company leases approximately 1.1 million square feet of office and laboratory space in two buildings in Boston, Massachusetts for a term of 15 years. Base rent payments commenced in December 2013, and will continue through December 2028. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease terms for an additional ten years. San Diego Lease In 2015, the Company entered into a lease agreement pursuant to which the Company leases approximately 170,000 square feet of office and laboratory space in San Diego, California for a term of 16 years. Base rent payments will commence in the second quarter of 2019, and will continue through May 2034. The Company utilizes this initial period as its lease term. The Company has an option to extend the lease term for up to two additional five -year terms. The Company placed this building in service in the second quarter of 2018. Operating Leases The Company’s operating leases relate to its real estate leases that are not classified as finance leases. Aggregate Lease Information Related to the Application of ASC 842 The following information is disclosed in accordance with ASC 842, which became effective January 1, 2019. The components of lease cost recorded in the Company’s condensed consolidated statement of operations were as follows: Three Months Ended March 31, 2019 (in thousands) Operating lease cost $ 2,639 Finance lease cost Amortization of leased assets 12,365 Interest on lease liabilities 13,449 Variable lease cost 6,762 Sublease income (1,484 ) Net lease cost $ 33,731 The Company’s variable lease cost during the three months ended March 31, 2019 primarily related to operating expenses, taxes and insurance associated with its finance leases. The Company’s sublease income during the three months ended March 31, 2019 primarily related to subleases for an insignificant portion of the Company’s corporate headquarters. The Company’s leases are included on its condensed consolidated balance sheets as follows: As of March 31, 2019 As of December 31, 2018 ^ (in thousands) Finance leases Property and equipment, net $ 473,129 $ 640,952 Total finance lease assets $ 473,129 $ 640,952 Capital lease obligations, current portion $ — $ 9,817 Other current liabilities 35,725 5,271 Capital lease obligations, excluding current portion — 19,658 Construction financing lease obligation, excluding current portion — 561,892 Long-term finance lease liabilities 560,381 — Total finance lease liabilities $ 596,106 $ 596,638 Operating leases Operating lease assets $ 60,573 $ — Total operating lease assets $ 60,573 $ — Other current liabilities $ 7,520 $ — Long-term operating lease liabilities 63,484 — Total operating lease liabilities $ 71,004 $ — ^ As reported in the Company’s 2018 Annual Report on Form 10-K. Maturities of the Company’s finance and operating lease liabilities in accordance with ASC 842 as of March 31, 2019 were as follows: Year Finance Leases Operating Leases Total (in thousands) Remainder of 2019 $ 61,339 $ 7,331 $ 68,670 2020 88,998 10,366 99,364 2021 87,365 8,658 96,023 2022 85,016 8,233 93,249 2023 84,092 8,151 92,243 Thereafter 512,804 46,212 559,016 Total lease payments 919,614 88,951 1,008,565 Less: amount representing interest (323,508 ) (17,947 ) (341,455 ) Present value of lease liabilities $ 596,106 $ 71,004 $ 667,110 The weighted-average remaining lease terms and discount rates related to the Company’s leases were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (in years) Finance leases 10.45 Operating leases 10.91 Weighted-average discount rate Finance leases 9.11 % Operating leases 4.05 % Please refer to Note O, “Additional Cash Flow Information,” for cash flow impact of the Company’s leases. Additional Lease Information Related to the Application of ASC 840 The following information is disclosed in accordance with ASC 840, Leases (Topic 840) (“ASC 840”), which was applicable until December 31, 2018. As of December 31, 2018, future minimum commitments under the Company’s real estate leases with initial terms of more than one year were as follows: Year Fan Pier San Diego Lease Other Total Lease (in thousands) 2019 $ 66,540 $ 5,324 $ 13,207 $ 85,071 2020 72,589 9,127 14,270 95,986 2021 72,589 9,127 12,529 94,245 2022 72,589 9,127 12,045 93,761 2023 72,589 9,530 11,952 94,071 Thereafter 389,855 119,864 65,472 575,191 Total minimum lease payments $ 746,751 $ 162,099 $ 129,475 $ 1,038,325 As of December 31, 2018, the Company’s total sublease income to be received related to its facility leases was $6.2 million . During the three months ended March 31, 2018 , rental expense was $4.6 million . As of December 31, 2018, the Company had outstanding capital leases totaling gross property and equipment of $94.8 million and accumulated depreciation of $34.0 million . The capital leases, which were related to equipment and leasehold improvements, bore interest at rates ranging from less than 1% to 6% per year. The Company’s capital lease amortization was included in depreciation expense during the three months ended March 31, 2018 . The following table set forth the Company’s future minimum payments due under capital leases as of December 31, 2018: Year (in thousands) 2019 $ 10,770 2020 7,282 2021 5,649 2022 3,300 2023 1,974 Thereafter 3,085 Total payments 32,060 Less: amount representing interest (2,585 ) Present value of payments $ 29,475

Stock-based Compensation Expens

Stock-based Compensation Expense and Share Repurchase	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation Expense and Share Repurchase	Stock-based Compensation Expense and Share Repurchase Stock-based compensation expense During the three months ended March 31, 2019 and 2018 , the Company recognized the following stock-based compensation expense: Three Months Ended March 31, 2019 2018 (in thousands) Stock-based compensation expense by type of award: Restricted stock and restricted stock units (including PSUs) $ 63,510 $ 50,418 Stock options 28,156 26,055 ESPP share issuances 2,577 2,128 Stock-based compensation expense related to inventories (452 ) (465 ) Total stock-based compensation included in costs and expenses $ 93,791 $ 78,136 Stock-based compensation expense by line item: Cost of sales $ 1,338 $ 813 Research and development expenses 59,715 48,488 Sales, general and administrative expenses 32,738 28,835 Total stock-based compensation included in costs and expenses 93,791 78,136 Income tax effect (39,524 ) (21,859 ) Total stock-based compensation included in costs and expenses, net of tax $ 54,267 $ 56,277 The following table sets forth the Company’s unrecognized stock-based compensation expense as of March 31, 2019 , by type of award and the weighted-average period over which that expense is expected to be recognized: As of March 31, 2019 Unrecognized Expense Weighted-average (in thousands) (in years) Type of award: Restricted stock and restricted stock units (including PSUs) $ 475,787 2.55 Stock options $ 193,321 2.84 ESPP share issuances $ 2,555 0.43 The following table summarizes information about stock options outstanding and exercisable as of March 31, 2019 : Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted-average Weighted-average Number Weighted-average (in thousands) (in years) (per share) (in thousands) (per share) $29.07–$40.00 252 1.67 $ 35.87 252 $ 35.87 $40.01–$60.00 437 3.20 $ 50.23 437 $ 50.23 $60.01–$80.00 525 5.02 $ 74.83 516 $ 74.82 $80.01–$100.00 2,481 6.95 $ 89.20 1,315 $ 89.81 $100.01–$120.00 622 5.88 $ 109.32 614 $ 109.24 $120.01–$140.00 773 6.36 $ 130.20 653 $ 130.24 $140.01–$160.00 1,287 8.82 $ 155.51 333 $ 155.35 $160.01–$180.00 502 8.30 $ 162.94 177 $ 162.95 $180.01–$187.53 1,823 9.65 $ 185.29 115 $ 182.72 Total 8,702 7.28 $ 124.11 4,412 $ 100.04 Share repurchase program The Company’s Board of Directors approved a share repurchase program, pursuant to which the Company is authorized to repurchase up to $500.0 million of its common stock between February 1, 2018 and December 31, 2019. Under the share repurchase program, the Company is authorized to purchase shares from time to time through open market or privately negotiated transactions. Such purchases may be made pursuant to Rule 10b5-1 plans or other means as determined by the Company’s management and in accordance with the requirements of the SEC. During the three months ended March 31, 2019 and 2018 , the Company repurchased 537,018 and 67,084 shares, respectively, of its common stock under the share repurchase program for an aggregate of $98.0 million (of which $4.0 million was accrued as of March 31, 2019 ) and $11.3 million , respectively, including commissions and fees. As of March 31, 2019 , there is a total of $52.0 million remaining for repurchases under the share repurchase program. The Company expects to fund further repurchases of its common stock through a combination of cash on hand and cash generated by operations.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to U.S. federal, state, and foreign income taxes. For the three months ended March 31, 2019 , the Company recorded a provision for income taxes of $51.5 million . The Company’s effective tax rate for the three months ended March 31, 2019 is lower than the U.S. statutory rate primarily due to excess tax benefits related to stock-based compensation and utilization of net operating losses to offset pre-tax operating income. The Company’s provision for income taxes for the three months ended March 31, 2019 increased compared to historical amounts due to the release of the Company’s valuation allowance on the majority of its net operating losses and other deferred tax assets as of December 31, 2018. Starting in the three months ended March 31, 2019 , the Company began recording a provision for income taxes on its pre-tax income using an estimated effective tax rate that approximates statutory rates. Due to the Company's ability to offset its pre-tax income against previously benefited net operating losses, it expects the majority of its tax provision to represent a non-cash expense until its net operating losses have been fully utilized. During the three months ended March 31, 2018 , the Company’s benefit from income taxes of $12.7 million included a benefit from income taxes of $21.9 million from excess tax benefits related to stock-based compensation partially offset by provisions for income taxes of $6.4 million related to BioAxone’s income taxes (as a result of an increase in the fair value of the contingent payments payable by the Company to BioAxone) and the Company’s U.S. state and foreign taxes. As noted above, the Company released the valuation allowance on the majority of net operating losses and other deferred tax assets and maintained a valuation allowance of $168.5 million related primarily to U.S. state and foreign tax attributes as of December 31, 2018. On a periodic basis, the Company reassesses any valuation allowances that it maintains on its deferred tax assets, weighing positive and negative evidence to assess the recoverability of the deferred tax assets. The Company has reviewed the tax positions taken, or to be taken, in its tax returns for all tax years currently open to examination by a taxing authority. Unrecognized tax benefits represent the aggregate tax effect of differences between tax return positions and the benefits recognized in the financial statements. As of March 31, 2019 and December 31, 2018 , the Company had $25.2 million and $19.5 million , respectively, of gross unrecognized tax benefits, which would affect the Company’s tax rate if recognized. The Company does not expect that its unrecognized tax benefits will materially increase within the next twelve months. The Company accrues interest and penalties related to unrecognized tax benefits as a component of its provision for income taxes. As of March 31, 2019 , no significant interest or penalties were accrued. The Company did not recognize any material interest or penalties related to uncertain tax positions during the three months ended March 31, 2019 and 2018 . As of March 31, 2019 , foreign earnings, which were not significant, have been retained indefinitely by foreign subsidiaries for indefinite reinvestment. Upon repatriation of those earnings, in the form of dividends or otherwise, the Company could be subject to withholding taxes payable to the various foreign countries. The Company files U.S. federal income tax returns and income tax returns in various state, local and foreign jurisdictions. The Company is no longer subject to any tax assessment from an income tax examination in the United States or any other major taxing jurisdiction for years before 2011, except where the Company has net operating losses or tax credit carryforwards that originate before 2011. The Company has various income tax audits ongoing at any time throughout the world. No adjustments have been reported for any jurisdiction under audit.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Guaranties and Indemnifications As permitted under Massachusetts law, the Company’s Articles of Organization and By-laws provide that the Company will indemnify certain of its officers and directors for certain claims asserted against them in connection with their service as an officer or director. The maximum potential amount of future payments that the Company could be required to make under these indemnification provisions is unlimited. However, the Company has purchased directors’ and officers’ liability insurance policies that could reduce its monetary exposure and enable it to recover a portion of any future amounts paid. No indemnification claims currently are outstanding, and the Company believes the estimated fair value of these indemnification arrangements is minimal. The Company customarily agrees in the ordinary course of its business to indemnification provisions in agreements with clinical trial investigators and sites in its drug development programs, sponsored research agreements with academic and not-for-profit institutions, various comparable agreements involving parties performing services for the Company and its real estate leases. The Company also customarily agrees to certain indemnification provisions in its drug discovery, development and commercialization collaboration agreements. With respect to the Company’s clinical trials and sponsored research agreements, these indemnification provisions typically apply to any claim asserted against the investigator or the investigator’s institution relating to personal injury or property damage, violations of law or certain breaches of the Company’s contractual obligations arising out of the research or clinical testing of the Company’s compounds or drug candidates. With respect to lease agreements, the indemnification provisions typically apply to claims asserted against the landlord relating to personal injury or property damage caused by the Company, to violations of law by the Company or to certain breaches of the Company’s contractual obligations. The indemnification provisions appearing in the Company’s collaboration agreements are similar to those for the other agreements discussed above, but in addition provide some limited indemnification for its collaborator in the event of third-party claims alleging infringement of intellectual property rights. In each of the cases above, the indemnification obligation generally survives the termination of the agreement for some extended period, although the Company believes the obligation typically has the most relevance during the contract term and for a short period of time thereafter. The maximum potential amount of future payments that the Company could be required to make under these provisions is generally unlimited. The Company has purchased insurance policies covering personal injury, property damage and general liability that reduce its exposure for indemnification and would enable it in many cases to recover all or a portion of any future amounts paid. The Company has never paid any material amounts to defend lawsuits or settle claims related to these indemnification provisions. Accordingly, the Company believes the estimated fair value of these indemnification arrangements is minimal. Other Contingencies The Company has certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a reserve for contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There were no material contingent liabilities accrued as of March 31, 2019 or December 31, 2018 .

Additional Cash Flow Informatio

Additional Cash Flow Information	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Additional Cash Flow Information	Additional Cash Flow Information The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in the Company’s condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 consisted of the following: Three Months Ended March 31, 2019 2018 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 2,650,134 $ 2,893,885 $ 1,665,412 $ 1,995,893 Prepaid expenses and other current assets 4,910 6,250 2,114 9,835 Other assets 3,209 1,397 — — Cash, cash equivalents and restricted cash per statement of cash flows $ 2,658,253 $ 2,901,532 $ 1,667,526 $ 2,005,728 Supplemental cash flow information related to the Company’s leases was as follows: Three Months Ended March 31, 2019 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,531 Operating cash flows from finance leases $ 11,910 Financing cash flows from finance leases $ 9,385 Right-of-use assets obtained in exchange for lease obligations Operating leases $ — Finance leases $ —

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
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 the Company and its wholly-owned subsidiaries. The Company's condensed consolidated financial statements for the interim period ended March 31, 2018 also include the financial results of BioAxone Biosciences, Inc. (“BioAxone”), a variable interest entity (“VIE”) that the Company consolidated from 2014 through December 31, 2018 . All material intercompany balances and transactions have been eliminated. The Company operates in one segment, pharmaceuticals. The Company has reclassified certain items from the prior year’s condensed consolidated financial statements to conform to the current year’s presentation. Certain information and footnote disclosures normally included in the Company’s 2018 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 March 31, 2019 and 2018 . 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, 2018 , which are contained in the 2018 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, research and development expenses, goodwill, 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	Recently Adopted Accounting Standards Leases In 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASC 842”), which amends a number of aspects of lease accounting and requires entities to recognize right-of-use assets and liabilities on the balance sheet. ASC 842 became effective on January 1, 2019. The Company has finalized its review of its portfolio of existing leases and current accounting policies and has concluded that the amended guidance results in the recognition of additional assets and corresponding liabilities on its balance sheets. The Company also has finalized changes to its controls to address the adoption and ongoing lease accounting and related disclosure requirements of the new standard. Until December 31, 2018, the Company applied build-to-suit accounting and was the deemed owner of its leased corporate headquarters in Boston and research site in San Diego, for which it was recognizing depreciation expense over the buildings’ useful lives and imputed interest on the corresponding construction financing lease obligations. Under the amended guidance that became effective January 1, 2019, the Company accounts for these buildings as finance leases, resulting in increased depreciation expense over the respective lease terms of 15-16 years, which are significantly shorter than the buildings’ useful lives of 40 years. The Company also expects a reduction in its imputed interest expense in the initial years of each finance lease term. In 2019, the Company expects an increase in operating expenses of approximately $26 million and a decrease in interest expense of approximately $13 million due to this change. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), which offered a transition option to entities adopting ASC 842. Under ASU 2018-11, entities could elect to apply ASC 842 using a modified-retrospective adoption approach resulting in a cumulative effect adjustment to accumulated deficit at the beginning of the year in which the new lease standard is adopted, rather than adjustments to the earliest comparative period presented in their financial statements. The Company adopted ASC 842 using the modified-retrospective method. As of January 1, 2019, the Company recorded a cumulative effect adjustment to increase its “ Accumulated deficit ” by $40.3 million related to the adjustments to its build-to-suit leases described in the previous paragraph. The Company elected the package of transition practical expedients for leases that commenced prior to January 1, 2019, allowing it not to reassess (i) whether any expired or existing contracts contain leases, (ii) the lease classification for any expired or existing leases and (iii) the initial indirect costs for any existing leases. Additionally, the Company recorded, upon adoption of ASC 842 on January 1, 2019, operating lease assets of $61.7 million and corresponding liabilities of $71.9 million related to its real estate leases that are not treated as finance leases under ASC 842. The difference between these assets and liabilities is primarily attributable to prepaid or accrued lease payments. The Company also reclassified amounts that were recorded as “Capital lease obligations, current portion” and “Capital lease obligations, excluding current portion” as of December 31, 2018 to “ Other current liabilities ” and “ Long-term finance lease liabilities ,” respectively, on January 1, 2019. These adjustments had no impact on the Company’s condensed consolidated statement of operations and had no impact on the Company’s accumulated deficit. The cumulative effect of applying ASC 842 on the Company’s condensed consolidated balance sheet as of January 1, 2019 was as follows: Balance as of Balance as of December 31, 2018 ^ Adjustments January 1, 2019 Assets (in thousands) Prepaid expenses and other current assets $ 140,819 $ (2,930 ) $ 137,889 Property and equipment, net 812,005 (53,920 ) 758,085 Deferred tax assets 1,499,672 11,236 1,510,908 Operating lease assets — 61,674 61,674 Total assets $ 6,245,898 $ 16,060 $ 6,261,958 Liabilities and Shareholders’ Equity Capital lease obligations, current portion $ 9,817 $ (9,817 ) $ — Other current liabilities 40,589 34,304 74,893 Capital lease obligations, excluding current portion 19,658 (19,658 ) — Construction financing lease obligation, excluding current portion 561,892 (561,892 ) — Long-term finance lease liabilities — 569,487 569,487 Long-term operating lease liabilities — 64,849 64,849 Other long-term liabilities 26,280 (20,903 ) 5,377 Accumulated deficit (2,989,478 ) (40,310 ) (3,029,788 ) Total liabilities and shareholders’ equity $ 6,245,898 $ 16,060 $ 6,261,958 ^ As reported in the Company’s 2018 Annual Report on Form 10-K. Please refer to Note K, “Leases,” for further information regarding the Company’s leases as well as certain disclosures required by ASC 842. 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. ASU 2017-12 became effective January 1, 2019. The adoption of ASU 2017-12 did not have a significant effect on the Company’s condensed consolidated financial statements. 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. ASU 2018-15 is effective on January 1, 2020. Early adoption is permitted. The Company currently is evaluating the impact the adoption of ASU 2018-15 may 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. ASU 2018-13 is effective 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. For a discussion of other recent accounting pronouncements please refer to Note A, “Nature of Business and Accounting Policies—Recent Accounting Pronouncements,” in the 2018 Annual Report on Form 10-K. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note A, “Nature of Business and Accounting Policies,” in its 2018 Annual Report on Form 10-K. The Company is disclosing changes in its accounting policies related to guidance that became effective January 1, 2019 in this Quarterly Report on Form 10-Q. Specifically, the Company has included its policy pursuant to its adoption of ASC 842 below. Leases At the inception of an arrangement, the Company determines whether the arrangement contains a lease. If a lease is identified in an arrangement, the Company recognizes a right-of-use asset and liability on its balance sheet and determines whether the lease should be classified as a finance or operating lease. The Company does not recognize assets or liabilities for leases with lease terms of less than 12 months. A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases. Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes its incremental borrowing rate at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease. The Company does not separate lease and non-lease components when determining which lease payments to include in the calculation of its lease assets and liabilities. Variable lease payments are expensed as incurred. If a lease includes an option to extend or terminate the lease, the Company reflects the option in the lease term if it is reasonably certain it will exercise the option. Finance leases are recorded in “ Property and equipment, net ,” “ Other current liabilities ” and “ Long-term finance lease liabilities ” on the Company’s condensed consolidated balance sheet. Operating leases are recorded in “ Operating lease assets ,” “ Other current liabilities ” and “ Long-term operating lease liabilities ” on the Company’s condensed consolidated balance sheet.

Basis of Presentation and Acc_3

Basis of Presentation and Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of new accounting pronouncements and changes in accounting principles	The cumulative effect of applying ASC 842 on the Company’s condensed consolidated balance sheet as of January 1, 2019 was as follows: Balance as of Balance as of December 31, 2018 ^ Adjustments January 1, 2019 Assets (in thousands) Prepaid expenses and other current assets $ 140,819 $ (2,930 ) $ 137,889 Property and equipment, net 812,005 (53,920 ) 758,085 Deferred tax assets 1,499,672 11,236 1,510,908 Operating lease assets — 61,674 61,674 Total assets $ 6,245,898 $ 16,060 $ 6,261,958 Liabilities and Shareholders’ Equity Capital lease obligations, current portion $ 9,817 $ (9,817 ) $ — Other current liabilities 40,589 34,304 74,893 Capital lease obligations, excluding current portion 19,658 (19,658 ) — Construction financing lease obligation, excluding current portion 561,892 (561,892 ) — Long-term finance lease liabilities — 569,487 569,487 Long-term operating lease liabilities — 64,849 64,849 Other long-term liabilities 26,280 (20,903 ) 5,377 Accumulated deficit (2,989,478 ) (40,310 ) (3,029,788 ) Total liabilities and shareholders’ equity $ 6,245,898 $ 16,060 $ 6,261,958 ^ As reported in the Company’s 2018 Annual Report on Form 10-K.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Schedule of disaggregation of revenue	Product revenues, net consisted of the following: Three Months Ended March 31, 2019 2018 (in thousands) SYMDEKO/SYMKEVI $ 320,275 $ 34,124 ORKAMBI 293,007 354,066 KALYDECO 243,971 249,539 Total product revenues, net $ 857,253 $ 637,729 Total revenues from external customers and collaborators by geographic region consisted of the following: Three Months Ended March 31, 2019 2018 (in thousands) United States $ 641,104 $ 482,667 Outside of the United States Europe 167,751 131,895 Other 49,580 26,237 Total revenues outside of the United States 217,331 158,132 Total revenues $ 858,435 $ 640,799

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	The following table sets forth the computation of basic and diluted net income per share for the periods ended: Three Months Ended March 31, 2019 2018 (in thousands, except per share amounts) Basic net income attributable to Vertex per common share calculation: Net income attributable to Vertex common shareholders $ 268,631 $ 210,263 Less: Undistributed earnings allocated to participating securities — (99 ) Net income attributable to Vertex common shareholders—basic $ 268,631 $ 210,164 Basic weighted-average common shares outstanding 255,695 253,231 Basic net income attributable to Vertex per common share $ 1.05 $ 0.83 Diluted net income attributable to Vertex per common share calculation: Net income attributable to Vertex common shareholders $ 268,631 $ 210,263 Less: Undistributed earnings allocated to participating securities — (97 ) Net income attributable to Vertex common shareholders—diluted $ 268,631 $ 210,166 Weighted-average shares used to compute basic net income per common share 255,695 253,231 Effect of potentially dilutive securities: Stock options 2,585 3,248 Restricted stock and restricted stock units (including PSUs) 1,870 2,013 Employee stock purchase program 25 34 Weighted-average shares used to compute diluted net income per common share 260,175 258,526 Diluted net income attributable to Vertex per common share $ 1.03 $ 0.81
Potential gross common equivalent shares	The Company did not include the securities in the following table in the computation of the net income per share attributable to Vertex common shareholders calculations because the effect would have been anti-dilutive during each period: Three Months Ended March 31, 2019 2018 (in thousands) Stock options 2,837 1,633 Unvested restricted stock and restricted stock units (including PSUs) 6 4

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Financial assets subject to fair value measurements (excluding VIE cash and cash equivalents, which are recorded as Restricted cash and cash equivalents (VIE))	The following table sets forth the Company’s financial assets and liabilities subject to fair value measurements (and does not include $1.5 billion and $ 1.4 billion of cash as of March 31, 2019 and December 31, 2018 , respectively): Fair Value Measurements as of March 31, 2019 Fair Value Hierarchy Total Level 1 Level 2 Level 3 (in thousands) Financial instruments carried at fair value (asset positions): Cash equivalents: Money market funds $ 1,354,656 $ 1,354,656 $ — $ — U.S. Treasury securities 5,996 5,996 — — Government-sponsored enterprise securities 11,786 11,786 — — Corporate debt securities 4,519 — 4,519 — Commercial paper 35,955 — 35,955 — Marketable securities: Corporate equity securities 210,874 192,207 18,667 — Government-sponsored enterprise securities 15,181 15,181 — — Corporate debt securities 231,572 — 231,572 — Commercial paper 126,523 — 126,523 — Prepaid expenses and other current assets: Foreign currency forward contracts 19,210 — 19,210 — Other assets: Foreign currency forward contracts 973 — 973 — Total financial assets $ 2,017,245 $ 1,579,826 $ 437,419 $ — Financial instruments carried at fair value (liability positions): Other current liabilities: Foreign currency forward contracts $ (310 ) $ — $ (310 ) $ — Other long-term liabilities: Foreign currency forward contracts (68 ) — (68 ) — Total financial liabilities $ (378 ) $ — $ (378 ) $ — Fair Value Measurements as of December 31, 2018 Fair Value Hierarchy Total Level 1 Level 2 Level 3 (in thousands) Financial instruments carried at fair value (asset positions): Cash equivalents: Money market funds $ 1,226,603 $ 1,226,603 $ — $ — U.S. Treasury securities 5,966 5,966 — — Government-sponsored enterprise securities 7,123 7,123 — — Commercial paper 58,268 — 58,268 — Marketable securities: Corporate equity securities 167,323 153,733 13,590 — U.S. Treasury securities 6,026 6,026 — — Government-sponsored enterprise securities 10,704 10,704 — — Corporate debt securities 233,665 — 233,665 — Commercial paper 100,390 — 100,390 — Prepaid expenses and other current assets: Foreign currency forward contracts 19,023 — 19,023 — Other assets: Foreign currency forward contracts 1,514 — 1,514 — Total financial assets $ 1,836,605 $ 1,410,155 $ 426,450 $ — Financial instruments carried at fair value (liability positions): Other current liabilities: Foreign currency forward contracts $ (340 ) $ — $ (340 ) $ — Other long-term liabilities: Foreign currency forward contracts (108 ) — (108 ) — Total financial liabilities $ (448 ) $ — $ (448 ) $ —

Marketable Securities and Equ_2

Marketable Securities and Equity Investments (Tables)	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Summary of cash equivalents and marketable securities	A summary of the Company’s cash equivalents and marketable securities, which are recorded at fair value (and do not include $1.5 billion and $ 1.4 billion of cash as of March 31, 2019 and December 31, 2018 , respectively), is shown below: Amortized Cost Gross Gross Fair Value (in thousands) As of March 31, 2019 Cash equivalents: Money market funds $ 1,354,656 $ — $ — $ 1,354,656 U.S. Treasury securities 5,996 — — 5,996 Government-sponsored enterprise securities 11,787 — (1 ) 11,786 Corporate debt securities 4,519 — — 4,519 Commercial paper 35,959 — (4 ) 35,955 Total cash equivalents 1,412,917 — (5 ) 1,412,912 Marketable securities: Government-sponsored enterprise securities 15,180 2 (1 ) 15,181 Corporate debt securities 231,516 88 (32 ) 231,572 Commercial paper 126,515 34 (26 ) 126,523 Total marketable debt securities 373,211 124 (59 ) 373,276 Corporate equity securities 133,157 79,093 (1,376 ) 210,874 Total marketable securities $ 506,368 $ 79,217 $ (1,435 ) $ 584,150 As of December 31, 2018 Cash equivalents: Money market funds $ 1,226,603 $ — $ — $ 1,226,603 U.S. Treasury securities 5,967 — (1 ) 5,966 Government-sponsored enterprise securities 7,124 — (1 ) 7,123 Commercial paper 58,271 — (3 ) 58,268 Total cash equivalents 1,297,965 — (5 ) 1,297,960 Marketable securities: U.S. Treasury securities 6,026 — — 6,026 Government-sponsored enterprise securities 10,704 — — 10,704 Corporate debt securities 234,088 27 (450 ) 233,665 Commercial paper 100,498 — (108 ) 100,390 Total marketable debt securities 351,316 27 (558 ) 350,785 Corporate equity securities 133,157 40,619 (6,453 ) 167,323 Total marketable securities $ 484,473 $ 40,646 $ (7,011 ) $ 518,108 Available-for-sale debt securities were recorded in the Company's condensed consolidated balance sheets at fair value as follows: As of March 31, 2019 As of December 31, 2018 (in thousands) Cash and cash equivalents $ 1,412,912 $ 1,297,960 Marketable securities 373,276 350,785 Total $ 1,786,188 $ 1,648,745 Available-for-sale debt securities by contractual maturity were as follows: As of March 31, 2019 As of December 31, 2018 (in thousands) Matures within one year $ 1,775,571 $ 1,647,500 Matures after one year through five years 10,617 1,245 Total $ 1,786,188 $ 1,648,745

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in accumulated other comprehensive (loss) income by component: Unrealized Holding Gains (Losses), Net of Tax Foreign Currency Translation Adjustment On Available-For-Sale Debt Securities On Foreign Currency Forward Contracts Total (in thousands) Balance at December 31, 2018 $ (11,227 ) $ (536 ) $ 12,422 $ 659 Other comprehensive income before reclassifications 4,967 596 5,126 10,689 Amounts reclassified from accumulated other comprehensive income — — (5,348 ) (5,348 ) Net current period other comprehensive income (loss) 4,967 596 (222 ) 5,341 Balance at March 31, 2019 $ (6,260 ) $ 60 $ 12,200 $ 6,000 Unrealized Holding Gains (Losses), Net of Tax Foreign Currency Translation Adjustment On Available-For-Sale Debt Securities On Equity Securities On Foreign Currency Forward Contracts Total (in thousands) Balance at December 31, 2017 $ (21,031 ) $ (594 ) $ 25,069 $ (15,016 ) $ (11,572 ) Other comprehensive loss before reclassifications (2,729 ) (460 ) — (7,639 ) (10,828 ) Amounts reclassified from accumulated other comprehensive income (loss) — — — 6,777 6,777 Net current period other comprehensive loss (2,729 ) (460 ) — (862 ) (4,051 ) Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard 949 — (25,069 ) — (24,120 ) Balance at March 31, 2018 $ (22,811 ) $ (1,054 ) $ — $ (15,878 ) $ (39,743 )

Hedging (Tables)

Hedging (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Cash Flow Hedging Instruments	The following table summarizes the notional amount of the Company’s outstanding foreign currency forward contracts designated as cash flow hedges under GAAP: As of March 31, 2019 As of December 31, 2018 Foreign Currency (in thousands) Euro $ 373,264 $ 335,179 British pound sterling 76,685 73,460 Australian dollar 70,889 52,820 Canadian dollar 40,089 43,759 Total foreign currency forward contracts $ 560,927 $ 505,218
Schedule of Foreign Exchange Contracts, Condensed Consolidated Statements of Operations	During the three months ended March 31, 2019 and 2018 , the Company recognized the following related to foreign currency forward contacts in its condensed consolidated statements of operations: Three Months Ended March 31, 2019 2018 (in thousands) Designated as hedging instruments - Reclassified from AOCI Product revenues, net $ 6,839 $ (6,485 ) Not designated as hedging instruments Other income, net $ 3,151 $ 1,539
Schedule of Foreign Exchange Contracts	The following table summarizes the fair value of the Company’s outstanding foreign currency forward contracts designated as cash flow hedges under GAAP included on its condensed consolidated balance sheets: As of March 31, 2019 Assets Liabilities Classification Fair Value Classification Fair Value (in thousands) Prepaid expenses and other current assets $ 19,210 Other current liabilities $ (310 ) Other assets 973 Other long-term liabilities (68 ) Total assets $ 20,183 Total liabilities $ (378 ) As of December 31, 2018 Assets Liabilities Classification Fair Value Classification Fair Value (in thousands) Prepaid expenses and other current assets $ 19,023 Other current liabilities $ (340 ) Other assets 1,514 Other long-term liabilities (108 ) Total assets $ 20,537 Total liabilities $ (448 )
Derivatives Offsetting	The following table summarizes the potential effect of offsetting derivatives by type of financial instrument designated as cash flow hedges under GAAP on the Company’s condensed consolidated balance sheets: As of March 31, 2019 Gross Amounts Recognized Gross Amounts Offset Gross Amounts Presented Gross Amounts Not Offset Legal Offset Foreign currency forward contracts (in thousands) Total assets $ 20,183 $ — $ 20,183 $ (378 ) $ 19,805 Total liabilities $ (378 ) $ — $ (378 ) $ 378 $ — As of December 31, 2018 Gross Amounts Recognized Gross Amounts Offset Gross Amounts Presented Gross Amounts Not Offset Legal Offset Foreign currency forward contracts (in thousands) Total assets $ 20,537 $ — $ 20,537 $ (448 ) $ 20,089 Total liabilities $ (448 ) $ — $ (448 ) $ 448 $ —

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventories by Type	Inventories consisted of the following: As of March 31, 2019 As of December 31, 2018 (in thousands) Raw materials $ 11,649 $ 9,677 Work-in-process 80,529 87,944 Finished goods 44,520 26,739 Total $ 136,698 $ 124,360

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lease Costs	The Company’s leases are included on its condensed consolidated balance sheets as follows: As of March 31, 2019 As of December 31, 2018 ^ (in thousands) Finance leases Property and equipment, net $ 473,129 $ 640,952 Total finance lease assets $ 473,129 $ 640,952 Capital lease obligations, current portion $ — $ 9,817 Other current liabilities 35,725 5,271 Capital lease obligations, excluding current portion — 19,658 Construction financing lease obligation, excluding current portion — 561,892 Long-term finance lease liabilities 560,381 — Total finance lease liabilities $ 596,106 $ 596,638 Operating leases Operating lease assets $ 60,573 $ — Total operating lease assets $ 60,573 $ — Other current liabilities $ 7,520 $ — Long-term operating lease liabilities 63,484 — Total operating lease liabilities $ 71,004 $ — ^ As reported in the Company’s 2018 Annual Report on Form 10-K. The components of lease cost recorded in the Company’s condensed consolidated statement of operations were as follows: Three Months Ended March 31, 2019 (in thousands) Operating lease cost $ 2,639 Finance lease cost Amortization of leased assets 12,365 Interest on lease liabilities 13,449 Variable lease cost 6,762 Sublease income (1,484 ) Net lease cost $ 33,731
Finance Lease, Liability, Maturity	Maturities of the Company’s finance and operating lease liabilities in accordance with ASC 842 as of March 31, 2019 were as follows: Year Finance Leases Operating Leases Total (in thousands) Remainder of 2019 $ 61,339 $ 7,331 $ 68,670 2020 88,998 10,366 99,364 2021 87,365 8,658 96,023 2022 85,016 8,233 93,249 2023 84,092 8,151 92,243 Thereafter 512,804 46,212 559,016 Total lease payments 919,614 88,951 1,008,565 Less: amount representing interest (323,508 ) (17,947 ) (341,455 ) Present value of lease liabilities $ 596,106 $ 71,004 $ 667,110
Lessee, Operating Lease, Liability, Maturity	Maturities of the Company’s finance and operating lease liabilities in accordance with ASC 842 as of March 31, 2019 were as follows: Year Finance Leases Operating Leases Total (in thousands) Remainder of 2019 $ 61,339 $ 7,331 $ 68,670 2020 88,998 10,366 99,364 2021 87,365 8,658 96,023 2022 85,016 8,233 93,249 2023 84,092 8,151 92,243 Thereafter 512,804 46,212 559,016 Total lease payments 919,614 88,951 1,008,565 Less: amount representing interest (323,508 ) (17,947 ) (341,455 ) Present value of lease liabilities $ 596,106 $ 71,004 $ 667,110
Weighted-Average Remaining Lease Terms and Discount Rates	The weighted-average remaining lease terms and discount rates related to the Company’s leases were as follows: Three Months Ended March 31, 2019 Weighted-average remaining lease term (in years) Finance leases 10.45 Operating leases 10.91 Weighted-average discount rate Finance leases 9.11 % Operating leases 4.05 %
Schedule of Future Minimum Lease Payments for Capital Leases	The following table set forth the Company’s future minimum payments due under capital leases as of December 31, 2018: Year (in thousands) 2019 $ 10,770 2020 7,282 2021 5,649 2022 3,300 2023 1,974 Thereafter 3,085 Total payments 32,060 Less: amount representing interest (2,585 ) Present value of payments $ 29,475
Schedule of Future Minimum Rental Payments for Operating Leases	The following information is disclosed in accordance with ASC 840, Leases (Topic 840) (“ASC 840”), which was applicable until December 31, 2018. As of December 31, 2018, future minimum commitments under the Company’s real estate leases with initial terms of more than one year were as follows: Year Fan Pier San Diego Lease Other Total Lease (in thousands) 2019 $ 66,540 $ 5,324 $ 13,207 $ 85,071 2020 72,589 9,127 14,270 95,986 2021 72,589 9,127 12,529 94,245 2022 72,589 9,127 12,045 93,761 2023 72,589 9,530 11,952 94,071 Thereafter 389,855 119,864 65,472 575,191 Total minimum lease payments $ 746,751 $ 162,099 $ 129,475 $ 1,038,325

Stock-based Compensation Expe_2

Stock-based Compensation Expense and Share Repurchase (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense by line item	During the three months ended March 31, 2019 and 2018 , the Company recognized the following stock-based compensation expense: Three Months Ended March 31, 2019 2018 (in thousands) Stock-based compensation expense by type of award: Restricted stock and restricted stock units (including PSUs) $ 63,510 $ 50,418 Stock options 28,156 26,055 ESPP share issuances 2,577 2,128 Stock-based compensation expense related to inventories (452 ) (465 ) Total stock-based compensation included in costs and expenses $ 93,791 $ 78,136 Stock-based compensation expense by line item: Cost of sales $ 1,338 $ 813 Research and development expenses 59,715 48,488 Sales, general and administrative expenses 32,738 28,835 Total stock-based compensation included in costs and expenses 93,791 78,136 Income tax effect (39,524 ) (21,859 ) Total stock-based compensation included in costs and expenses, net of tax $ 54,267 $ 56,277
Unrecognized stock-based compensation expense, net of estimated forfeitures	The following table sets forth the Company’s unrecognized stock-based compensation expense as of March 31, 2019 , by type of award and the weighted-average period over which that expense is expected to be recognized: As of March 31, 2019 Unrecognized Expense Weighted-average (in thousands) (in years) Type of award: Restricted stock and restricted stock units (including PSUs) $ 475,787 2.55 Stock options $ 193,321 2.84 ESPP share issuances $ 2,555 0.43
Stock options outstanding and exercisable	The following table summarizes information about stock options outstanding and exercisable as of March 31, 2019 : Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted-average Weighted-average Number Weighted-average (in thousands) (in years) (per share) (in thousands) (per share) $29.07–$40.00 252 1.67 $ 35.87 252 $ 35.87 $40.01–$60.00 437 3.20 $ 50.23 437 $ 50.23 $60.01–$80.00 525 5.02 $ 74.83 516 $ 74.82 $80.01–$100.00 2,481 6.95 $ 89.20 1,315 $ 89.81 $100.01–$120.00 622 5.88 $ 109.32 614 $ 109.24 $120.01–$140.00 773 6.36 $ 130.20 653 $ 130.24 $140.01–$160.00 1,287 8.82 $ 155.51 333 $ 155.35 $160.01–$180.00 502 8.30 $ 162.94 177 $ 162.95 $180.01–$187.53 1,823 9.65 $ 185.29 115 $ 182.72 Total 8,702 7.28 $ 124.11 4,412 $ 100.04

Additional Cash Flow Informat_2

Additional Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Cash Flow Statement	The cash, cash equivalents and restricted cash at the beginning and ending of each period presented in the Company’s condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 consisted of the following: Three Months Ended March 31, 2019 2018 Beginning of period End of period Beginning of period End of period (in thousands) Cash and cash equivalents $ 2,650,134 $ 2,893,885 $ 1,665,412 $ 1,995,893 Prepaid expenses and other current assets 4,910 6,250 2,114 9,835 Other assets 3,209 1,397 — — Cash, cash equivalents and restricted cash per statement of cash flows $ 2,658,253 $ 2,901,532 $ 1,667,526 $ 2,005,728
Lease, Supplemental Cash Flow Information	Supplemental cash flow information related to the Company’s leases was as follows: Three Months Ended March 31, 2019 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,531 Operating cash flows from finance leases $ 11,910 Financing cash flows from finance leases $ 9,385 Right-of-use assets obtained in exchange for lease obligations Operating leases $ — Finance leases $ —

Basis of Presentation and Acc_4

Basis of Presentation and Accounting Policies - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Jan. 01, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2011
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments | segment	1
Cumulative effect adjustment to accumulated deficit		$ (40,310)		$ 9,229
Operating lease assets	$ 60,573		$ 61,674
Total operating lease liabilities	$ 71,004
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment to accumulated deficit		(40,310)		$ 33,349
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expected future increase (decrease) in operating expenses		(26,000)
Expected future increase (decrease) in interest expense		13,000
Operating lease assets		$ 61,674	61,700
Total operating lease liabilities			71,900
Accounting Standards Update 2016-02 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment to accumulated deficit			$ 40,300
Fan Pier Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Length of lease					15 years

Basis of Presentation and Acc_5

Basis of Presentation and Accounting Policies - Cumulative Effect of applying ASC 842 to the Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	$ 130,009	$ 137,889	$ 140,819
Property and equipment, net	742,559	758,085	812,005
Deferred tax assets	1,467,518	1,510,908	1,499,672
Operating lease assets	60,573	61,674
Total assets	6,543,114	6,261,958	6,245,898
Capital lease obligations, current portion			9,817
Other current liabilities		74,893	40,589
Capital lease obligations, excluding current portion			19,658
Construction financing lease obligation, excluding current portion			561,892
Long-term finance lease liabilities	560,381	569,487
Long-term operating lease liabilities	63,484	64,849
Other long-term liabilities	5,997	5,377	26,280
Accumulated deficit	(2,761,157)	(3,029,788)	(2,989,478)
Total liabilities and shareholders’ equity	$ 6,543,114	6,261,958	6,245,898
Accounting Standards Update 2016-02
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets			(2,930)
Property and equipment, net			(53,920)
Deferred tax assets			11,236
Operating lease assets		$ 61,700	61,674
Total assets			16,060
Capital lease obligations, current portion			(9,817)
Other current liabilities			34,304
Capital lease obligations, excluding current portion			(19,658)
Construction financing lease obligation, excluding current portion			(561,892)
Long-term finance lease liabilities			569,487
Long-term operating lease liabilities			64,849
Other long-term liabilities			(20,903)
Accumulated deficit			(40,310)
Total liabilities and shareholders’ equity			$ 16,060

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Early access sales accrual	$ 382,703	$ 354,404
Contract liabilities	$ 51,400	$ 24,900

Revenue Recognition - Schedule

Revenue Recognition - Schedule of disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	$ 858,435	$ 640,799
United States
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	641,104	482,667
Europe
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	167,751	131,895
Other
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	49,580	26,237
Total revenues outside of the United States
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	217,331	158,132
Product revenues, net
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	857,253	637,729
SYMDEKO
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	320,275	34,124
ORKAMBI
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	293,007	354,066
KALYDECO
Disaggregation of Revenue [Line Items]
Disaggregation of revenue	$ 243,971	$ 249,539

Collaborative Arrangements an_2

Collaborative Arrangements and Acquisitions - CRISPR Therapeutics AG (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2015USD ($)target
CRISPR Therapeutics
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Right to license, number of targets (up to) | target			6
Collaborative arrangement, up-front payment			$ 75
Collaborative arrangement, development and regulatory potential milestone payments maximum			$ 420
CTX001 Co-Co
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement research and development expenses	$ 7	$ 3.6

Collaborative Agreements and Ac

Collaborative Agreements and Acquisitions - Other In-License Agreements (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2016
Moderna Therapeutics, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, up-front payment		$ 20
Collaborative arrangement, development and regulatory potential milestone payments maximum		$ 275
Arbor Biotechnologies, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, up-front payment	$ 30
Collaborative arrangement, investment in collaborative partner, pursuant to convertible loan agreement	15
Collaborative arrangement, development and regulatory potential milestone payments maximum	$ 337.5

Collaborative Arrangements an_3

Collaborative Arrangements and Acquisitions - BioAxone Biosciences, Inc. (Details) - USD ($) $ in Thousands	Oct. 01, 2014	Mar. 31, 2019	Mar. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest		$ 0	$ 17,038
(Increase) decrease in fair value of contingent payments			24,000
BioAxone Biosciences Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, up-front payment	$ 10,000		$ 10,000

Collaborative Arrangements an_4

Collaborative Arrangements and Acquisitions - Parion Sciences, Inc. (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Parion Sciences, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, up-front payment	$ 5

Collaborative Arrangements an_5

Collaborative Arrangements and Acquisitions - Concert Pharmaceuticals (Details) - Concert Pharmaceuticals $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, development and commercialization rights potential maximum milestone payments	$ 160
Collaborative arrangement, additional maximum milestone payments based on regulatory approval	$ 90

Collaborative Arrangements an_6

Collaborative Arrangements and Acquisitions - Merck KGaA (Details) - Merck KGaA $ in Millions	1 Months Ended
	Dec. 31, 2018USD ($)	Jan. 31, 2017USD ($)pre-clinical_stage_programclinical-stage_programdevelopment_program
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Right to license, number of development programs | development_program		4
Right to license, number of clinical stage programs | clinical-stage_program		2
Number of pre-clinical stage programs | pre-clinical_stage_program		2
Collaborative arrangement, up-front payment | $	$ 65	$ 230

Collaborative Arrangements an_7

Collaborative Arrangements and Acquisitions - Janssen Pharmaceuticals, Inc. (Details) $ in Millions	12 Months Ended
	Dec. 31, 2014USD ($)
Janssen Pharmaceuticals, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, up-front payment	$ 60

Collaborative Arrangements an_8

Collaborative Arrangements and Acquisitions - Cystic Fibrosis Foundation Therapeutics Incorporated (Details) - Cystic Fibrosis Foundation Therapeutics Incorporated - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2016
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additional milestone payments	$ 0
Collaborative funding		$ 75,000,000
Additional collaborative funding		$ 6,000,000

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Earnings Per Share Computation Statement (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic net income attributable to Vertex per common share calculation:
Net income attributable to Vertex common shareholders	$ 268,631	$ 210,263
Less: Undistributed earnings allocated to participating securities	0	(99)
Net income attributable to Vertex common shareholders—basic	$ 268,631	$ 210,164
Basic weighted-average common shares outstanding (in shares)	255,695	253,231
Basic net income (loss) attributable to Vertex per common share (in dollars per share)	$ 1.05	$ 0.83
Diluted net income attributable to Vertex per common share calculation:
Less: Undistributed earnings allocated to participating securities	$ 0	$ (97)
Net income attributable to Vertex common shareholders—diluted	$ 268,631	$ 210,166
Effect of potentially dilutive securities:
Employee stock purchase program (in shares)	25	34
Weighted-average shares used to compute diluted net income per common share (in shares)	260,175	258,526
Diluted net income attributable to Vertex per common share (in dollars per share)	$ 1.03	$ 0.81
Stock options
Effect of potentially dilutive securities:
Share-based payment arrangements (in shares)	2,585	3,248
Restricted stock and restricted stock units (including PSUs)
Effect of potentially dilutive securities:
Share-based payment arrangements (in shares)	1,870	2,013

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring basis - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financial instruments carried at fair value (asset positions):
Total financial assets	$ 2,017,245	$ 1,836,605
Financial instruments carried at fair value (liability positions):
Total financial liabilities	(378)	(448)
Level 1
Financial instruments carried at fair value (asset positions):
Total financial assets	1,579,826	1,410,155
Financial instruments carried at fair value (liability positions):
Total financial liabilities	0	0
Level 2
Financial instruments carried at fair value (asset positions):
Total financial assets	437,419	426,450
Financial instruments carried at fair value (liability positions):
Total financial liabilities	(378)	(448)
Level 3
Financial instruments carried at fair value (asset positions):
Total financial assets	0	0
Financial instruments carried at fair value (liability positions):
Total financial liabilities	0	0
Prepaid expenses and other current assets | Foreign currency forward contracts
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	19,210	19,023
Prepaid expenses and other current assets | Foreign currency forward contracts | Level 1
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	0	0
Prepaid expenses and other current assets | Foreign currency forward contracts | Level 2
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	19,210	19,023
Prepaid expenses and other current assets | Foreign currency forward contracts | Level 3
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	0	0
Other assets | Foreign currency forward contracts
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	973
Total financial assets		1,514
Other assets | Foreign currency forward contracts | Level 1
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	0
Total financial assets		0
Other assets | Foreign currency forward contracts | Level 2
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	973
Total financial assets		1,514
Other assets | Foreign currency forward contracts | Level 3
Financial instruments carried at fair value (asset positions):
Foreign currency forward contracts	0
Total financial assets		0
Other current liabilities | Foreign currency forward contracts
Financial instruments carried at fair value (liability positions):
Derivative liability current	(310)	(340)
Other current liabilities | Foreign currency forward contracts | Level 1
Financial instruments carried at fair value (liability positions):
Derivative liability current	0	0
Other current liabilities | Foreign currency forward contracts | Level 2
Financial instruments carried at fair value (liability positions):
Derivative liability current	(310)	(340)
Other current liabilities | Foreign currency forward contracts | Level 3
Financial instruments carried at fair value (liability positions):
Derivative liability current	0	0
Other long-term liabilities | Foreign currency forward contracts
Financial instruments carried at fair value (liability positions):
Derivative liability, noncurrent	(68)	(108)
Other long-term liabilities | Foreign currency forward contracts | Level 1
Financial instruments carried at fair value (liability positions):
Derivative liability, noncurrent	0	0
Other long-term liabilities | Foreign currency forward contracts | Level 2
Financial instruments carried at fair value (liability positions):
Derivative liability, noncurrent	(68)	(108)
Other long-term liabilities | Foreign currency forward contracts | Level 3
Financial instruments carried at fair value (liability positions):
Derivative liability, noncurrent	0	0
Money market funds
Financial instruments carried at fair value (asset positions):
Cash equivalents	1,354,656	1,226,603
Money market funds | Level 1
Financial instruments carried at fair value (asset positions):
Cash equivalents	1,354,656	1,226,603
Money market funds | Level 2
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Money market funds | Level 3
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
U.S. Treasury securities
Financial instruments carried at fair value (asset positions):
Cash equivalents	5,996	5,966
Marketable securities		6,026
U.S. Treasury securities | Level 1
Financial instruments carried at fair value (asset positions):
Cash equivalents	5,996	5,966
Marketable securities		6,026
U.S. Treasury securities | Level 2
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities		0
U.S. Treasury securities | Level 3
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities		0
Government-sponsored enterprise securities
Financial instruments carried at fair value (asset positions):
Cash equivalents	11,786	7,123
Marketable securities	15,181	10,704
Government-sponsored enterprise securities | Level 1
Financial instruments carried at fair value (asset positions):
Cash equivalents	11,786	7,123
Marketable securities	15,181	10,704
Government-sponsored enterprise securities | Level 2
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities	0	0
Government-sponsored enterprise securities | Level 3
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities	0	0
Corporate debt securities
Financial instruments carried at fair value (asset positions):
Cash equivalents	4,519
Marketable securities	231,572	233,665
Corporate debt securities | Level 1
Financial instruments carried at fair value (asset positions):
Cash equivalents	0
Marketable securities	0	0
Corporate debt securities | Level 2
Financial instruments carried at fair value (asset positions):
Cash equivalents	4,519
Marketable securities	231,572	233,665
Corporate debt securities | Level 3
Financial instruments carried at fair value (asset positions):
Cash equivalents	0
Marketable securities	0	0
Commercial paper
Financial instruments carried at fair value (asset positions):
Cash equivalents	35,955	58,268
Marketable securities	126,523	100,390
Commercial paper | Level 1
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities	0	0
Commercial paper | Level 2
Financial instruments carried at fair value (asset positions):
Cash equivalents	35,955	58,268
Marketable securities	126,523	100,390
Commercial paper | Level 3
Financial instruments carried at fair value (asset positions):
Cash equivalents	0	0
Marketable securities	0	0
Corporate equity securities
Financial instruments carried at fair value (asset positions):
Marketable securities	210,874	167,323
Corporate equity securities | Level 1
Financial instruments carried at fair value (asset positions):
Marketable securities	192,207	153,733
Corporate equity securities | Level 2
Financial instruments carried at fair value (asset positions):
Marketable securities	18,667	13,590
Corporate equity securities | Level 3
Financial instruments carried at fair value (asset positions):
Marketable securities	$ 0	$ 0

Earnings Per Share - Potential

Earnings Per Share - Potential Gross Common Equivalent Shares (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per share (in shares)	2,837	1,633
Unvested restricted stock and restricted stock units (including PSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per share (in shares)	6	4

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Billions	Mar. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Cash	$ 1.5	$ 1.4

Marketable Securities and Equ_3

Marketable Securities and Equity Investments - Summary of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale Debt Securities
Fair Value	$ 1,786,188	$ 1,648,745
Equity Securities, FV-NI and without Readily Determinable Fair Value [Abstract]
Amortized Cost	506,368	484,473
Gross Unrealized Gains	79,217	40,646
Gross Unrealized Losses	(1,435)	(7,011)
Fair Value	584,150	518,108
Money market funds
Summary of cash, cash equivalents and marketable securities
Amortized Cost	1,354,656	1,226,603
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	1,354,656	1,226,603
U.S. Treasury securities
Summary of cash, cash equivalents and marketable securities
Amortized Cost	5,996	5,967
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	5,996	5,966
Available-for-sale Debt Securities
Amortized Cost		6,026
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		6,026
Government-sponsored enterprise securities
Summary of cash, cash equivalents and marketable securities
Amortized Cost	11,787	7,124
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	11,786	7,123
Available-for-sale Debt Securities
Amortized Cost	15,180	10,704
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(1)	0
Fair Value	15,181	10,704
Corporate debt securities
Summary of cash, cash equivalents and marketable securities
Amortized Cost	4,519
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	4,519
Available-for-sale Debt Securities
Amortized Cost	231,516	234,088
Gross Unrealized Gains	88	27
Gross Unrealized Losses	(32)	(450)
Fair Value	231,572	233,665
Commercial paper
Summary of cash, cash equivalents and marketable securities
Amortized Cost	35,959	58,271
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(3)
Fair Value	35,955	58,268
Available-for-sale Debt Securities
Amortized Cost	126,515	100,498
Gross Unrealized Gains	34	0
Gross Unrealized Losses	(26)	(108)
Fair Value	126,523	100,390
Cash Equivalents
Summary of cash, cash equivalents and marketable securities
Amortized Cost	1,412,917	1,297,965
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	(5)
Fair Value	1,412,912	1,297,960
Total marketable debt securities
Available-for-sale Debt Securities
Amortized Cost	373,211	351,316
Gross Unrealized Gains	124	27
Gross Unrealized Losses	(59)	(558)
Fair Value	373,276	350,785
Corporate equity securities
Equity Securities, FV-NI and without Readily Determinable Fair Value [Abstract]
Amortized Cost	133,157	133,157
Gross Unrealized Gains	79,093	40,619
Gross Unrealized Losses	(1,376)	(6,453)
Fair Value	$ 210,874	$ 167,323

Marketable Securities and Equ_4

Marketable Securities and Equity Investments - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Summary of cash, cash equivalents and marketable securities
Cash	$ 1,500,000,000		$ 1,400,000,000
Other-than-temporary declines in fair value of available-for-sale debt securities	0	$ 0
Gross realized gains or losses	0	0
Unrealized gains to other (expense) income, net	43,600,000	95,500,000
Payments to acquire investment	0	$ 21,500,000
Other assets
Summary of cash, cash equivalents and marketable securities
Equity securities without readily determinable fair value, amount	13,600,000
Corporate equity securities
Summary of cash, cash equivalents and marketable securities
Equity Securities, FV-NI	$ 210,874,000		$ 167,323,000

Marketable Securities and Equ_5

Marketable Securities and Equity Investments - Available-for-Sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Matures within one year	$ 1,775,571	$ 1,647,500
Matures after one year through five years	10,617	1,245
Debt Securities, Available-for-sale	$ 1,786,188	$ 1,648,745

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 4,435,203	$ 2,042,306
Total changes in other comprehensive income (loss)	5,341	(4,051)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		9,229	$ (40,310)
Ending Balance	4,723,313	2,430,821
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(11,227)	(21,031)
Other comprehensive income before reclassifications	4,967	(2,729)
Amounts reclassified from accumulated other comprehensive income	0	0
Total changes in other comprehensive income (loss)	4,967	(2,729)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		949
Ending Balance	(6,260)	(22,811)
Unrealized Holding Gains (Losses), Net of Tax, On Available-For-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(536)	(594)
Other comprehensive income before reclassifications	596	(460)
Amounts reclassified from accumulated other comprehensive income	0	0
Total changes in other comprehensive income (loss)	596	(460)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0
Ending Balance	60	(1,054)
Unrealized Holding Gains (Losses), Net of Tax, On Equity Securities, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		25,069
Other comprehensive income before reclassifications		0
Amounts reclassified from accumulated other comprehensive income		0
Total changes in other comprehensive income (loss)		0
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(25,069)
Ending Balance		0
Unrealized Holding Gains (Losses), Net of Tax, On Foreign Currency Forward Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(15,016)
Other comprehensive income before reclassifications		(7,639)
Amounts reclassified from accumulated other comprehensive income		6,777
Total changes in other comprehensive income (loss)		(862)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		0
Ending Balance		(15,878)
Unrealized Holding Gains (Losses), Net of Tax, On Foreign Currency Forward Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	12,422
Other comprehensive income before reclassifications	5,126
Amounts reclassified from accumulated other comprehensive income	(5,348)
Total changes in other comprehensive income (loss)	(222)
Ending Balance	12,200
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	659	(11,572)
Other comprehensive income before reclassifications	10,689	(10,828)
Amounts reclassified from accumulated other comprehensive income	(5,348)	6,777
Total changes in other comprehensive income (loss)	5,341	(4,051)
Amounts reclassified to accumulated deficit pursuant to adoption of new accounting standard		(24,120)
Ending Balance	$ 6,000	$ (39,743)

Hedging - Narrative (Details)

Hedging - Narrative (Details) - Foreign currency forward contracts $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Cash flow hedging | Minimum
Derivative [Line Items]
Derivative term	1 month
Cash flow hedging | Maximum
Derivative [Line Items]
Derivative term	18 months
Not designated as hedging instruments
Derivative [Line Items]
Derivative term	1 year
Not designated as hedging instruments | Cash flow hedging
Derivative [Line Items]
Notional amount of foreign currency forward contract	$ 220.9

Hedging - Notional Amount (Deta

Hedging - Notional Amount (Details) - Foreign currency forward contracts - Designated as hedging instruments - Cash flow hedging - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional amount of foreign currency forward contract	$ 560,927	$ 505,218
Euro
Derivative [Line Items]
Notional amount of foreign currency forward contract	373,264	335,179
British pound sterling
Derivative [Line Items]
Notional amount of foreign currency forward contract	76,685	73,460
Australian dollar
Derivative [Line Items]
Notional amount of foreign currency forward contract	70,889	52,820
Canadian dollar
Derivative [Line Items]
Notional amount of foreign currency forward contract	$ 40,089	$ 43,759

Hedging - Cash Flow Hedging Ins

Hedging - Cash Flow Hedging Instruments (Details) - Unrealized Holding Gains (Losses), Net of Tax, On Foreign Currency Forward Contracts - Reclassification out of Accumulated Other Comprehensive Income - Foreign currency forward contracts - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Revenues	$ 6,839	$ (6,485)
Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Other Income	$ 3,151	$ 1,539

Hedging - Derivative Fair Value

Hedging - Derivative Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Foreign currency forward contracts | Cash flow hedging
Derivative [Line Items]
Total assets	$ 20,183	$ 20,537
Total liabilities	(378)	(448)
Designated as hedging instruments | Foreign currency forward contracts | Cash flow hedging
Derivative [Line Items]
Total assets	20,183	20,537
Total liabilities	(378)	(448)
Prepaid expenses and other current assets | Designated as hedging instruments
Derivative [Line Items]
Fair Value - assets	19,210	19,023
Other current liabilities | Designated as hedging instruments
Derivative [Line Items]
Fair Value - liabilities	(310)	(340)
Other assets | Designated as hedging instruments
Derivative [Line Items]
Fair Value - assets	973	1,514
Other long-term liabilities | Designated as hedging instruments
Derivative [Line Items]
Fair Value - liabilities	$ (68)	$ (108)

Hedging - Offsetting Derivative

Hedging - Offsetting Derivatives (Details) - Cash flow hedging - Foreign currency forward contracts - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Offsetting Derivative Assets [Abstract]
Gross Amounts Recognized	$ 20,183	$ 20,537
Offsetting Derivative Liabilities [Abstract]
Gross Amounts Recognized	(378)	(448)
Designated as hedging instruments
Offsetting Derivative Assets [Abstract]
Gross Amounts Recognized	20,183	20,537
Gross Amounts Offset	0	0
Gross Amounts Presented	20,183	20,537
Gross Amounts Not Offset	(378)	(448)
Legal Offset	19,805	20,089
Offsetting Derivative Liabilities [Abstract]
Gross Amounts Recognized	(378)	(448)
Gross Amounts Offset	0	0
Gross Amounts Presented	(378)	(448)
Gross Amounts Not Offset	378	448
Legal Offset	$ 0	$ 0

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 11,649	$ 9,677
Work-in-process	80,529	87,944
Finished goods	44,520	26,739
Total Inventories	$ 136,698	$ 124,360

Revolving Credit Facility (Deta

Revolving Credit Facility (Details) $ in Millions	1 Months Ended
	Oct. 31, 2016USD ($)
Line of Credit Facility [Line Items]
Proceeds from lines of credit	$ 300
Line of credit facility additional borrowing capacity	300
Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	$ 500
Debt covenant, consolidated leverage ratio	3
Debt covenant, minimum consolidated EBITDA	$ 200
Base Rate | Minimum | Line of Credit
Line of Credit Facility [Line Items]
Interest rate, stated percentage	0.75%
Base Rate | Maximum | Line of Credit
Line of Credit Facility [Line Items]
Interest rate, stated percentage	1.50%
Eurodollar | Minimum | Line of Credit
Line of Credit Facility [Line Items]
Interest rate, stated percentage	1.75%
Eurodollar | Maximum | Line of Credit
Line of Credit Facility [Line Items]
Interest rate, stated percentage	2.50%

Leases - Narative (Details)

Leases - Narative (Details) ft² in Thousands, $ in Millions	Dec. 02, 2015ft²term_extension	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2011ft²leasebuilding	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Sublease income related to facility leases			$ 6.2
Rent expense		$ 4.6
Total capital leased assets, gross			94.8
Capital leases accumulated depreciation			$ 34
Fan Pier Leases
Property, Plant and Equipment [Line Items]
Number of leases | lease				2
Area of real estate property (in square feet) | ft²				1,100
Number of buildings under lease agreement | building				2
Length of lease				15 years
San Diego Lease
Property, Plant and Equipment [Line Items]
Area of real estate property (in square feet) | ft²	170
Length of lease					16 years
Amount of optional renewal terms | term_extension	2
Optional renewal term length	5 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 2,639
Amortization of leased assets	12,365
Interest on lease liabilities	13,449
Variable lease cost	6,762
Sublease income	(1,484)
Net lease cost	$ 33,731

Leases - Balance Sheet Classifi

Leases - Balance Sheet Classification of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Property and equipment, net	$ 473,129		$ 640,952
Total finance lease assets	473,129		640,952
Capital lease obligations, current portion			9,817
Other current liabilities	35,725		5,271
Capital lease obligations, excluding current portion			19,658
Construction financing lease obligation, excluding current portion			561,892
Long-term finance lease liabilities	560,381	$ 569,487
Total finance lease liabilities	596,106		$ 596,638
Operating lease assets	60,573	61,674
Other current liabilities	7,520
Long-term operating lease liabilities	63,484	$ 64,849
Total operating lease liabilities	$ 71,004

Leases - Maturities of Operatin

Leases - Maturities of Operating and Financing Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finance Leases
Remainder of 2019	$ 61,339
2020	88,998
2021	87,365
2022	85,016
2023	84,092
Thereafter	512,804
Total lease payments	919,614
Less: amount representing interest	(323,508)
Present value of lease liabilities	596,106	$ 596,638
Operating Leases
Remainder of 2019	7,331
2020	10,366
2021	8,658
2022	8,233
2023	8,151
Thereafter	46,212
Total lease payments	88,951
Less: amount representing interest	(17,947)
Present value of lease liabilities	71,004
Total
Remainder of 2019	68,670
2020	99,364
2021	96,023
2022	93,249
2023	92,243
Thereafter	559,016
Total lease payments	1,008,565
Less: amount representing interest	(341,455)
Present value of lease liabilities	$ 667,110

Leases - Weighted-Average Remai

Leases - Weighted-Average Remaining Lease Terms and Discount Rates (Details)	Mar. 31, 2019
Leases [Abstract]
Weighted average remaining lease term, finance leases	10 years 5 months 12 days
Weighted-average remaining lease term, operating leases	10 years 10 months 28 days
Weighted average discount rate, finance leases	9.11%
Weighted average discount rate, operating leases	4.05%

Leases - Future Minimum Commitm

Leases - Future Minimum Commitments Under Real Estate Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Property Subject to or Available for Operating Lease [Line Items]
2019	$ 85,071
2020	95,986
2021	94,245
2022	93,761
2023	94,071
Thereafter	575,191
Total minimum lease payments	1,038,325
Fan Pier Leases
Property Subject to or Available for Operating Lease [Line Items]
2019	66,540
2020	72,589
2021	72,589
2022	72,589
2023	72,589
Thereafter	389,855
Total minimum lease payments	746,751
San Diego Lease
Property Subject to or Available for Operating Lease [Line Items]
2019	5,324
2020	9,127
2021	9,127
2022	9,127
2023	9,530
Thereafter	119,864
Total minimum lease payments	162,099
Other Leases
Property Subject to or Available for Operating Lease [Line Items]
2019	13,207
2020	14,270
2021	12,529
2022	12,045
2023	11,952
Thereafter	65,472
Total minimum lease payments	$ 129,475

Leases - Capital Leases (Detail

Leases - Capital Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 10,770
2020	7,282
2021	5,649
2022	3,300
2023	1,974
Thereafter	3,085
Total payments	32,060
Less: amount representing interest	(2,585)
Present value of payments	$ 29,475

Stock-based Compensation Expe_3

Stock-based Compensation Expense and Share Repurchase - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	$ 93,791	$ 78,136
Stock-based compensation expense related to inventories	(452)	(465)
Share-based compensation expense by type of award	93,791	78,136
Income tax effect	(39,524)	(21,859)
Total stock-based compensation included in costs and expenses, net of tax	54,267	56,277
Cost of sales
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	1,338	813
Research and development expenses
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	59,715	48,488
Sales, general and administrative expenses
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	32,738	28,835
Restricted stock and restricted stock units (including PSUs)
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	63,510	50,418
Type of award:
Unrecognized Expense	$ 475,787
Weighted-average Recognition Period	2 years 6 months 18 days
Stock options
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	$ 28,156	26,055
Type of award:
Unrecognized Expense	$ 193,321
Weighted-average Recognition Period	2 years 10 months 2 days
ESPP share issuances
Stock-based compensation expense:
Total stock-based compensation included in costs and expenses	$ 2,577	$ 2,128
Type of award:
Unrecognized Expense	$ 2,555
Weighted-average Recognition Period	5 months 5 days

Stock-based Compensation Expe_4

Stock-based Compensation Expense and Share Repurchase - Stock Options Outstanding and Exercisable (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price range, options outstanding (in shares) | shares	8,702
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	7 years 3 months 11 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 124.11
Exercise price range, options exercisable (in shares) | shares	4,412
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 100.04
$29.07–$40.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	29.07
Exercise price, high end of range (in dollars per share)	$ 40
Exercise price range, options outstanding (in shares) | shares	252
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	1 year 8 months 1 day
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 35.87
Exercise price range, options exercisable (in shares) | shares	252
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 35.87
$40.01–$60.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	40.01
Exercise price, high end of range (in dollars per share)	$ 60
Exercise price range, options outstanding (in shares) | shares	437
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	3 years 2 months 12 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 50.23
Exercise price range, options exercisable (in shares) | shares	437
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 50.23
$60.01–$80.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	60.01
Exercise price, high end of range (in dollars per share)	$ 80
Exercise price range, options outstanding (in shares) | shares	525
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	5 years 7 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 74.83
Exercise price range, options exercisable (in shares) | shares	516
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 74.82
$80.01–$100.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	80.01
Exercise price, high end of range (in dollars per share)	$ 100
Exercise price range, options outstanding (in shares) | shares	2,481
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6 years 11 months 12 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 89.20
Exercise price range, options exercisable (in shares) | shares	1,315
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 89.81
$100.01–$120.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	100.01
Exercise price, high end of range (in dollars per share)	$ 120
Exercise price range, options outstanding (in shares) | shares	622
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	5 years 10 months 17 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 109.32
Exercise price range, options exercisable (in shares) | shares	614
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 109.24
$120.01–$140.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	120.01
Exercise price, high end of range (in dollars per share)	$ 140
Exercise price range, options outstanding (in shares) | shares	773
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6 years 4 months 10 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 130.20
Exercise price range, options exercisable (in shares) | shares	653
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 130.24
$140.01–$160.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	140.01
Exercise price, high end of range (in dollars per share)	$ 160
Exercise price range, options outstanding (in shares) | shares	1,287
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8 years 9 months 26 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 155.51
Exercise price range, options exercisable (in shares) | shares	333
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 155.35
$160.01–$180.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	160.01
Exercise price, high end of range (in dollars per share)	$ 180
Exercise price range, options outstanding (in shares) | shares	502
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8 years 3 months 18 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 162.94
Exercise price range, options exercisable (in shares) | shares	177
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 162.95
$180.01–$187.53
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	180.01
Exercise price, high end of range (in dollars per share)	$ 181.60
Exercise price range, options outstanding (in shares) | shares	1,823
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	9 years 7 months 24 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 185.29
Exercise price range, options exercisable (in shares) | shares	115
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 182.72

Stock-based Compensation Expe_5

Stock-based Compensation Expense and Share Repurchase - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Share repurchased	$ 103,839	$ 11,251
Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Number of shares authorized to be repurchased	500,000,000
Shares repurchased (shares)	537,018	67,084
Share repurchased	$ 98,000	$ 11,300
Shares repurchased, accrued liabilities	$ 4,000
Number of shares remaining for repurchases under the repurchase program	52,000,000

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Schedule of Collaborative Arrangement Agreements [Line Items]
Provision for (benefit from) income taxes	$ 51,534,000	$ (12,659,000)
Excess tax benefits related to stock-based compensation		21,900,000
Unrecognized tax benefits	25,200,000		$ 19,500,000
Income taxes, interest and penalties accrued	0
Increase in unrecognized tax benefits is reasonably possible	0
Income taxes, material interest or penalties related to uncertain tax positions	$ 0	0
BioAxone Biosciences Inc.
Schedule of Collaborative Arrangement Agreements [Line Items]
Provision for (benefit from) income taxes		$ 6,400,000
Domestic and Foreign Tax Authority
Schedule of Collaborative Arrangement Agreements [Line Items]
Deferred tax assets, valuation allowance			$ 168,500,000

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Indemnification claims	$ 0
Contingent liabilities	$ 0	$ 0

Additional Cash Flow Informat_3

Additional Cash Flow Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 2,893,885	$ 2,650,134	$ 1,995,893	$ 1,665,412
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	2,901,532	2,658,253	2,005,728	1,667,526
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	6,250	4,910	9,835	2,114
Other assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents	$ 1,397	$ 3,209	$ 0	$ 0

Additional Cash Flow Informat_4

Additional Cash Flow Information - Supplemental Cash Flow Information Related to Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Cash Flow, Lessee [Abstract]
Operating cash flows from operating leases	$ 2,531
Operating cash flows from finance leases	11,910
Financing cash flows from finance leases	9,385
Right-of-use assets obtained in exchange for lease obligations
Operating leases	0
Finance leases	$ 0