Sarepta Therapeutics (SRPT) 10-Q 8 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 03, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	SRPT
Entity Registrant Name	Sarepta Therapeutics, Inc.
Entity Central Index Key	873,303
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		66,442,402

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 410,375	$ 599,691
Short-term investments	538,769	479,369
Accounts receivable	42,985	29,468
Inventory	104,126	83,605
Other current assets	42,989	36,511
Total current assets	1,139,244	1,228,644
Property and equipment, net of accumulated depreciation of $22,124 and $18,022 as of June 30, 2018 and December 31, 2017, respectively	57,624	43,156
Intangible assets, net of accumulated amortization of $5,100 and $4,145 as of June 30, 2018 and December 31, 2017, respectively	14,857	14,355
Other assets	35,435	21,809
Total assets	1,247,160	1,307,964
Current liabilities:
Accounts payable	17,382	8,467
Accrued expenses	72,477	68,982
Current portion of long-term debt	9,514	6,175
Deferred revenue	3,303	3,316
Other current liabilities	2,011	1,392
Total current liabilities	104,687	88,332
Long-term debt	429,925	424,876
Deferred rent and other	13,501	5,539
Total liabilities	548,113	518,747
Commitments and contingencies (Note 16)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 3,333,333 shares authorized; none issued and outstanding
Common stock, $0.0001 par value, 99,000,000 shares authorized; 66,346,248 and 64,791,670 issued and outstanding at June 30, 2018 and December 31, 2017, respectively	7	6
Additional paid-in capital	2,061,039	2,006,598
Accumulated other comprehensive loss	(361)	(379)
Accumulated deficit	(1,361,638)	(1,217,008)
Total stockholders’ equity	699,047	789,217
Total liabilities and stockholders’ equity	$ 1,247,160	$ 1,307,964

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Property and equipment, accumulated depreciation	$ 22,124	$ 18,022
Intangible assets, accumulated amortization	$ 5,100	$ 4,145
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	3,333,333	3,333,333
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	99,000,000	99,000,000
Common stock, issued	66,346,248	64,791,670
Common stock, outstanding	66,346,248	64,791,670

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Product, net	$ 73,529	$ 35,011	$ 138,133	$ 51,353
Total revenues	73,529	35,011	138,133	51,353
Costs and expenses:
Cost of sales (excluding amortization of in-licensed rights)	6,735	506	12,317	729
Research and development	122,848	58,908	169,052	88,027
Selling, general and administrative	47,156	36,069	90,497	62,285
EXONDYS 51 litigation and license charges		2,839		2,839
Amortization of in-licensed rights	217	28	433	57
Total costs and expenses	176,956	98,350	272,299	153,937
Operating loss	(103,427)	(63,339)	(134,166)	(102,584)
Other (loss) income:
Gain from sale of Priority Review Voucher				125,000
Interest (expense) income and other, net	(5,218)	184	(9,703)	519
Other (loss) income	(5,218)	184	(9,703)	125,519
(Loss) income before income tax expense (benefit)	(108,645)	(63,155)	(143,869)	22,935
Income tax expense (benefit)	622	(109)	761	1,891
Net (loss) income	(109,267)	(63,046)	(144,630)	21,044
Other comprehensive (loss) income:
Unrealized gain on cash equivalents and short-term investments	282	17	18	82
Total other comprehensive income	282	17	18	82
Comprehensive (loss) income	$ (108,985)	$ (63,029)	$ (144,612)	$ 21,126
Net (loss) income per share
Basic (loss) earnings per share	$ (1.67)	$ (1.15)	$ (2.22)	$ 0.38
Diluted (loss) earnings per share	$ (1.67)	$ (1.15)	$ (2.22)	$ 0.37
Weighted average number of shares of common stock used in computing:
Basic (loss) earnings per share	65,484	54,976	65,060	54,913
Diluted (loss) earnings per share	65,484	54,976	65,060	56,176

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net (loss) income	$ (144,630)	$ 21,044
Adjustments to reconcile net (loss) income to cash flows from operating activities:
Gain from sale of Priority Review Voucher		(125,000)
Depreciation and amortization	5,125	3,409
Amortization of investment discount	(2,828)	(260)
Non-cash interest expense	9,958	117
Loss on disposal of assets	37	604
Stock-based compensation	25,805	16,177
Changes in operating assets and liabilities, net:
Net increase in accounts receivable	(13,517)	(12,563)
Net increase in inventory	(20,521)	(28,941)
Net increase in other assets	(29,866)	(9,285)
Net increase (decrease) in accounts payable, accrued expenses, deferred revenue and other liabilities	17,515	(8,337)
Net cash used in operating activities	(152,922)	(143,035)
Cash flows from investing activities:
Purchase of property and equipment	(20,863)	(7,336)
Purchase of intangible assets	(1,556)	(1,601)
Purchase of available-for-sale securities	(295,823)	(100,348)
Proceeds from sale of Priority Review Voucher		125,000
Purchases of restricted investment	(353)
Maturity of restricted investment		10,695
Maturity of available-for-sale securities	249,243	163,521
Net cash (used in) provided by investing activities	(69,352)	189,931
Cash flows from financing activities:
Proceeds from revolving line of credit	173,354
Payments on mortgage loans	(1,265)
Payments on revolving line of credit	(173,653)
Proceeds from exercise of options and purchase of stock under the Employee Stock Purchase Program	34,386	4,086
Repayments of long-term debt		(5,054)
Net cash provided by (used in) financing activities	32,822	(968)
(Decrease) increase in cash and cash equivalents	(189,452)	45,928
Cash, cash equivalents and restricted cash:
Beginning of period	599,827	122,556
End of period	410,375	168,484
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	410,375	168,348
Restricted cash in other assets		$ 136
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]		us-gaap:OtherAssetsNoncurrent
Total cash, cash equivalents and restricted cash	410,375	$ 168,484
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	6,058	538
Supplemental schedule of non-cash investing activities and financing activities:
Shares withheld for taxes	5,750	309
Reclassification of long term investments to short term investments	9,980
Intangible assets included in accrued expenses	294	265
Asset held for sale		1,529
Accrual for debt issuance costs related to the term loans	600	$ 400
Property and equipment included in accrued expenses	$ 289

ORGANIZATION AND NATURE OF BUSI

ORGANIZATION AND NATURE OF BUSINESS	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
ORGANIZATION AND NATURE OF BUSINESS	1. ORGANIZATION AND NATURE OF BUSINESS Sarepta Therapeutics, Inc. (together with its wholly-owned subsidiaries, “Sarepta” or the “Company”) is a commercial-stage biopharmaceutical company focused on the discovery and development of unique RNA-targeted therapeutics, gene therapy and other genetic medicine approaches for the treatment of rare neuromuscular diseases. Applying its proprietary, highly-differentiated and innovative platform technologies, the Company is able to target a broad range of diseases and disorders. Its first commercial product in the U.S., EXONDYS 51 ® In addition to advancing its exon-skipping product candidates for DMD, including eteplirsen, golodirsen, casimersen and SRP-5051, the Company is working with several strategic partners under various agreements to research and develop multiple treatment approaches to DMD, which include Nationwide Children’s Hospital, Genethon, Duke University and Summit (Oxford) Ltd. (“Summit”). In November 2016, the Company submitted a marketing authorization application (“MAA”) for eteplirsen to the European Medicines Agency (“EMA”) and the application was validated in December 2016. On June 1, 2018, the Committee for Medicinal Products for Human Use (“CHMP”) of the EMA, adopted a negative opinion for eteplirsen. The Company has requested a re-examination of the opinion, and that a Scientific Advisory Group (“SAG”) on DMD be called so that neuromuscular specialists, experienced with working with treatments for these patients, can provide expert guidance and insight into, among other things, the validity of the external controls used and the importance of certain functional endpoints, including for instance, the relevance of meaningful slowing pulmonary decline in patients with this disease that is difficult to treat. The re-examination process is expected to be completed by year-end 2018. The Company has also initiated a market access program (“MAP”) for eteplirsen in select countries in Europe, North America, South America and Asia where it currently has not been approved. The MAP provides a mechanism through which physicians can prescribe eteplirsen, within their professional responsibility, to patients who meet pre-specified medical and other criteria and can secure funding. The Company commenced shipments through the MAP. In addition, the Company contracted with third party distributors and service providers to distribute eteplirsen in certain areas outside the U.S., such as Israel and certain countries in the Middle East, on a named patient basis. As of June 30, 2018, the Company had approximately $950.2 million of cash, cash equivalents and investments, consisting of $410.4 million of cash and cash equivalents, $538.8 million of short-term investments, and $1.0 million of restricted investment. The Company believes that its balance of cash, cash equivalents and investments as of the date of the issuance of this report is sufficient to fund its current operational plan for at least the next twelve months, though it may pursue additional cash resources through public or private debt and equity financings, seek additional government contracts and establish collaborations with or license its technology to other companies.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), reflect the accounts of Sarepta Therapeutics, Inc. and its wholly-owned subsidiaries. All intercompany transactions between and among its consolidated subsidiaries have been eliminated. Management has determined that the Company operates in one segment: discovering, developing, manufacturing and delivering therapies to patients with DMD. The Company’s CEO, as the chief operating decision-maker, manages and allocates resources to the operations of the Company on a total company basis. The Company’s research and development organization is responsible for the research and discovery of new product candidates and supports development and registration efforts for potential future products. The Company’s supply chain organization manages the development of the manufacturing processes, clinical trial supply and commercial product supply. The Company’s commercial organization is responsible for commercialization of EXONDYS 51 in the U.S. and internationally. The Company is supported by other back-office general and administration functions. Consistent with this decision-making process, the Company’s CEO uses consolidated, single-segment financial information for purposes of evaluating performance, forecasting future period financial results, allocating resources and setting incentive targets. Estimates and Uncertainties The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include revenue recognition, inventory, convertible debt, valuation of stock-based awards, research and development expenses and income tax. Concentration of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist of accounts receivable from customers and cash, cash equivalents and investments held at financial institutions. As of June 30, 2018, the majority of the Company’s accounts receivable arose from product sales in the U.S. and all customers have standard payment terms which generally require payment within 30 to 60 days. Outside of the U.S., the payment terms range between 45 and 120 days. Three individual customers accounted for 44%, 35% and 19% of net product revenues for the six months ended June 30, 2018 and 61%, 26% and 11% of accounts receivable from product sales as of June 30, 2018. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in the customers’ credit profile. As of June 30, 2018, the Company believes that such customers are of high credit quality. As of June 30, 2018 the Company’s cash equivalents and investments were concentrated at a single financial institution, which potentially exposes the Company to credit risks. However, the Company does not believe that there is significant risk of non-performance by the financial institution. Significant Accounting Policies For details about the Company’s accounting policies, please read Note 2, Summary of Significant Accounting Policies and Recent Accounting Pronouncements The Company has adopted Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“ASC 606”) effective as of January 1, 2018. The Company has chosen to use the full retrospective transition method, under which it is required to revise its consolidated financial statements for the years ended December 31, 2016 and 2017 as well as any applicable interim periods within those years, as if ASC 606 had been effective for those periods. Under ASC 606, the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (1) identify the contracts with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied. For all contracts that fall into the scope of ASC 606, only one performance obligation has been identified by the Company: to timely deliver drug products to the customer’s designated warehouses. Product Revenues The Company distributes its product principally through a limited number of specialty distributor and specialty pharmacies in the U.S. and certain distributors in the European Union (“EU”), Israel and Middle East (collectively, “Customers”). The Customers subsequently resell the product to patients and health care providers. The Company provides no right of return to the Customers except in cases of shipping error or product defect. Product revenues are recognized when the Customers take control of the product, which typically occurs upon delivery to the Customers. For both the three and six months ended June 30, 2018, the majority of the revenues recognized were generated by the specialty distributor and specialty pharmacies in the U.S. Variable Consideration Product revenues are recorded at the net sales price (“transaction price”) which includes estimated reserves for variable consideration, such as Medicaid rebates, governmental chargebacks, including Public Health Service (“PHS”) chargebacks, prompt payment discounts, co-pay assistance and distribution fees. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if no payment is required by the Company) or a current liability (if a payment is required by the Company). These reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contracts. Additional details relating to variable consideration follows: • Medicaid rebates relate to the Company’s estimated obligations to states under established reimbursement arrangements. Rebate reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability which is included in accrued expenses. • Governmental chargebacks, including PHS chargebacks, relate to the Company’s estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices that the Company charges to wholesalers. The wholesaler charges the Company for the difference between what the wholesaler pays for the products and the ultimate selling price to the qualified healthcare providers. Chargeback reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider from the wholesaler, and the Company generally issues credits for such amounts within a few weeks of receiving notification of resale from the wholesaler. • Prompt payment discounts relate to the Company’s estimated obligations for credits to be granted to a specialty pharmacy for remitting payment on its purchases within established incentive periods. Reserves for prompt payment discounts are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. • Co-pay assistance relates to financial assistance provided to qualified patients, whereby the Company may assist them with prescription drug co-payments required by the patient’s insurance provider. Reserves for co-pay assistance are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability which is included in accrued expenses. • Distribution fees relate to fees paid to Customers in the distribution channel that provide the Company with inventory management, data and distribution services and are generally accounted for as a reduction of revenue. To the extent that the services received are distinct from the Company’s sale of products to the Customer, these payments are accounted for as selling, general and administrative expenses. The impact of adopting ASC 606 was not material. There have not been any other material changes to the Company’s accounting policies as of June 30, 2018. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, “ Leases (Topic 842) Leases In March 2017, the FASB issued ASU No. 2017-08, “ Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In June 2018, the FASB issued ASU 2018-07, “ Compensation - Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting

COLLABORATION, LICENSE AND MANU

COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS	3. COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS Myonexus Warrant Agreement In May 2018, the Company entered into a Warrant to Purchase Common Stock Agreement (“Warrant Agreement”) with Myonexus Therapeutics, Inc. (“Myonexus”). Pursuant to the terms of the Warrant Agreement, the Company made an up-front payment of $60.0 million to purchase an exclusive option to acquire Myonexus at a pre-negotiated, fixed price plus sales-related and regulatory-related contingent payments. Prior to the exercise of the option to acquire Myonexus, the Company may be required to make additional development milestone payments to Myonexus of up to $45.0 million over an approximately two-year evaluation period. The up-front payment of $60.0 million to Myonexus provides the Company with rights to potential future benefits associated with Myonexus’s ongoing research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the up-front payment of $60.0 million was expensed as incurred and classified as research and development expense in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss during the three and six months ended June 30, 2018. The additional development milestones payments of up to $45.0 million will also be recorded to research and development expense when (and if) incurred. The Company considered whether it would have to consolidate the operations of Myonexus and concluded that, while Myonexus is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Myonexus. Brammer Manufacturing Agreement In June 2018, the Company entered into a Development, Commercial Manufacturing and Supply Agreement (“Brammer Manufacturing Agreement”), with Brammer Bio MA, LLC (“Brammer”). Pursuant to the terms of the Brammer Manufacturing Agreement, Brammer agreed to provide the Company with access to clinical and commercial manufacturing capacity for its gene therapy programs. As part of the Brammer Manufacturing Agreement, the Company will purchase product in batches from Brammer, subject to minimum and maximum annual purchase requirements. Further, the Company: (i) was required to make a $20.0 million advance payment to Brammer upon execution of the agreement, (ii) is required to make two non-refundable payments of $5.0 million each to Brammer in the third and fourth quarter of 2018 to be used in the specification, selection, and procurement of the related process equipment to be utilized under the agreement, and (iii) is required to make a $10.0 million quarterly capacity access fee payment to Brammer throughout the term of the agreement. However, through June 30, 2019, a reduced quarterly capacity access fee will be in effect as Brammer works towards achieving full capacity at its facility. In addition, one-tenth of the $20.0 million advance payment will be applied as a credit to the quarterly capacity access fees due and payable from July 1, 2019 through December 31, 2021, resulting in a net capacity access fee of $8.0 million. The term of the Brammer Manufacturing Agreement will continue for a period of six years following the first regulatory approval of a product manufactured under the agreement. The term will automatically renew for successive two years unless the Company notifies Brammer of its intention not to renew (no less than twenty-four months prior to the expiration of the term). The Company also has the ability to terminate the agreement prior to expiration but would be required to continue remitting capacity access fees to Brammer for up to eight additional quarters. The Company has determined that the Brammer Manufacturing Agreement does not contain an embedded lease because it does not convey the right to control the use of the facility or related equipment. This conclusion was based on the Company’s inability or right to control physical access to Brammer’s facility and the related equipment, and the ability of one or more parties, other than the Company, to take more than a minor amount of the output that will be produced during the term of the agreement. As of June 30, 2018, the $20.0 million advance payment was recorded as an other non-current asset in the accompanying unaudited condensed consolidated balance sheet. The advance payment will be amortized over its expected economic benefit to research and development expense, prior to regulatory approval of the related product, commencing upon the first batch delivery to the Company. Upon regulatory approval, amortization expense will be classified to cost of sales. In the event the Company does not expect services under the Brammer Manufacturing Agreement to be rendered, the capitalized advance payment will be charged to expense. The two $5.0 million process equipment fee payments will also be capitalized as an other asset when paid and amortized to expense in a manner similar to the advance payment described above. Capacity access fee payments made prior to the first batch delivery to the Company will also be capitalized as an other asset when paid and amortized to expense in a manner similar to the advance payment described above. Capacity access fee payments made subsequent to the first batch delivery to the Company will be expensed as incurred to research and development expense, prior to regulatory approval of the related product. Upon regulatory approval, the expense associated with capacity access fee payments will be classified to cost of sales.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	4. FAIR VALUE MEASUREMENTS The Company has certain financial assets that are recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. • Level 1 — quoted prices for identical instruments in active markets; • Level 2 — quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets; and • Level 3 — valuations derived from valuation techniques in which one or more significant value drivers are unobservable. The tables below present information about the Company’s financial assets that are measured and carried at fair value and indicate the level within the fair value hierarchy of valuation techniques it utilizes to determine such fair value: Fair Value Measurement as of June 30, 2018 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 211,197 $ 211,197 $ — $ — Commercial paper 189,622 — 189,622 — Government and government agency bonds 278,512 278,512 — — Corporate bonds 85,594 85,594 — — Certificates of deposit $ 1,001 1,001 — — Total $ 765,926 $ 576,304 $ 189,622 $ — Fair Value Measurement as of December 31, 2017 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 352,370 $ 352,370 $ — $ — Commercial paper 133,368 — 133,368 — Government and government agency bonds 294,717 284,745 9,972 — Corporate bonds 127,956 127,956 — — Certificates of deposit 648 648 — — Total $ 909,059 $ 765,719 $ 143,340 $ — The Company’s assets with fair value categorized as Level 1 within the fair value hierarchy include money market funds, government and government agency bonds, corporate bonds and certificates of deposit. Certain of the government and government agency bonds and corporate bonds are publically traded fixed income securities and are presented as cash equivalents on the unaudited condensed consolidated balance sheets as of June 30, 2018. The Company’s assets with fair value categorized as Level 2 within the fair value hierarchy consist of commercial paper and government and government agency bonds. These assets have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, through income-based approaches utilizing market observable data. The carrying amounts reported in the unaudited condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, accounts payable, and revolving line of credit approximate fair value because of the immediate or short-term maturity of these financial instruments. The carrying amounts for the term loan approximate fair value based on market activity for other debt instruments with similar characteristics and comparable risk.

CASH, CASH EQUIVALENTS AND MARK

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	6 Months Ended
	Jun. 30, 2018
Cash And Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	5. CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES The following table summarizes the Company’s financial assets with maturities of less than 90 days from the date of purchase included in cash equivalents in the unaudited condensed consolidated balance sheets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Money market funds $ 211,197 $ 352,370 Corporate bonds 14,959 16,720 Government and government agency bonds — 49,972 Total $ 226,156 $ 419,062 It is the Company’s policy to mitigate credit risk in its financial assets by maintaining a well-diversified portfolio that limits the amount of exposure as to maturity and investment type. The weighted average maturity of the Company’s available-for-sale securities as of June 30, 2018 and December 31, 2017 was approximately two and seven months, respectively. The following tables summarize the Company’s cash, cash equivalents and short-term investments for each of the periods indicated: As of June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value (in thousands) Cash and money market funds $ 395,416 $ — $ — 395,416 Commercial paper 189,622 — — 189,622 Government and government agency bonds 278,680 5 (173 ) 278,512 Corporate bonds 85,787 — (193 ) 85,594 Total $ 949,505 $ 5 $ (366 ) 949,144 As reported: Cash and cash equivalents $ 410,375 $ — $ — 410,375 Short-term investments 539,130 5 (366 ) 538,769 Total $ 949,505 $ 5 $ (366 ) 949,144 As of December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value (in thousands) Cash and money market funds $ 532,999 $ — $ — $ 532,999 Commercial paper - current 133,368 — — 133,368 Government and government agency bonds - current 294,915 2 (200 ) 294,717 Corporate bonds Current 118,121 — (145 ) 117,976 Non-current 10,016 — (36 ) 9,980 Total $ 1,089,419 $ 2 $ (381 ) $ 1,089,040 As reported: Cash and cash equivalents $ 599,698 $ 2 $ (9 ) $ 599,691 Short-term investments 479,705 — (336 ) 479,369 Long-term investments 10,016 — (36 ) 9,980 Total $ 1,089,419 $ 2 $ (381 ) $ 1,089,040

ACCOUNTS RECEIVABLE AND RESERVE

ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES	6 Months Ended
	Jun. 30, 2018
Receivables Net Current [Abstract]
ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES	6. ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES The Company’s accounts receivable arise from product sales, government research contracts and other grants. They are generally stated at the invoiced amount and do not bear interest. The accounts receivable from product sales represents receivables due from the Company’s specialty distributor and specialty pharmacies in the U.S. as well as certain distributors in the EU, Israel and the Middle East. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in the customers’ credit profiles. The Company provides reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are written-off against the established reserve. As of June 30, 2018, the credit profiles for the Company’s customers are deemed to be in good standing and write-offs of accounts receivable are not considered necessary. Historically, no accounts receivable amounts related to government research contracts and other grants have been written off and, thus, an allowance for doubtful accounts receivable related to government research contracts and other grants is not considered necessary. The following table summarizes the components of the Company’s accounts receivable for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Product sales, net of discounts and allowances $ 42,056 $ 28,539 Government contract receivables 929 929 Total accounts receivable $ 42,985 $ 29,468 The balance for government contract receivables for both periods presented is subject to government audit and will not be collected until the completion of the audit. The following table summarizes an analysis of the change in reserves for discounts and allowances for the periods indicated: Chargebacks Rebates Prompt Pay Other Total (in thousands) Balance, as of December 31, 2017 $ 995 $ 6,959 $ 169 $ 464 $ 8,587 Provision 6,490 11,178 1,094 2,460 21,222 Payments/credits (6,622 ) (1,978 ) (917 ) (1,813 ) (11,330 ) Balance, as of June 30, 2018 $ 863 $ 16,159 $ 346 $ 1,111 $ 18,479 The following table summarizes the total reserves above included in the Company’s unaudited condensed consolidated balance sheets for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Reduction to accounts receivable $ 1,612 $ 1,285 Component of accrued expenses 16,867 7,302 Total reserves $ 18,479 $ 8,587

INVENTORY

INVENTORY	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
INVENTORY	7. INVENTORY Inventories are stated at the lower of cost and net realizable value with cost determined on a first-in, first-out basis. The Company capitalizes inventory costs associated with products following regulatory approval when future commercialization is considered probable and the future economic benefit is expected to be realized. EXONDYS 51 which may be used in clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes. The following table summarizes the components of the Company’s inventory for the period indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Raw materials $ 64,525 $ 53,875 Work in progress 37,107 27,442 Finished goods 2,494 2,288 Total inventory $ 104,126 $ 83,605 The Company periodically reviews its inventories for excess amounts or obsolescence and writes down obsolete or otherwise unmarketable inventory to its estimated net realizable value. Additionally, though the Company’s product is subject to strict quality control and monitoring which it performs throughout the manufacturing processes, certain batches or units of product may not meet quality specifications resulting in a charge to cost of sales.

OTHER CURRENT ASSETS AND OTHER

OTHER CURRENT ASSETS AND OTHER NON-CURRENT ASSETS	6 Months Ended
	Jun. 30, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
OTHER CURRENT ASSETS AND OTHER NON-CURRENT ASSETS	8. OTHER CURRENT ASSETS AND OTHER NON-CURRENT ASSETS The following table summarizes the Company’s other current assets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Manufacturing-related deposits and prepaids $ 15,338 $ 18,650 Leasehold improvement receivable 10,409 — Prepaid clinical and preclinical expenses 7,286 5,175 Prepaid maintenance and license fees 2,745 1,711 Prepaid research expenses 2,472 2,896 Prepaid commercial expenses 374 1,589 Asset held for sale — 1,501 Other prepaids 2,497 2,726 Other 1,868 2,263 Total other current assets $ 42,989 $ 36,511 The following table summarizes the Company’s other non-current assets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Manufacturing-related deposits $ 22,633 $ — Prepaid clinical expenses 8,680 7,488 Alternative minimum tax credit 2,881 3,315 Restricted investment 1,001 784 Long-term available-for-sale securities — 9,980 Other 240 242 Total other non-current assets $ 35,435 $ 21,809

ACCRUED EXPENSES

ACCRUED EXPENSES	6 Months Ended
	Jun. 30, 2018
Payables And Accruals [Abstract]
ACCRUED EXPENSES	9. ACCRUED EXPENSES The following table summarizes the Company’s accrued expenses for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Accrued employee compensation costs $ 17,949 $ 14,402 Product revenue related reserves 16,867 7,302 Accrued clinical and preclinical costs 11,068 15,975 Accrued contract manufacturing costs 8,421 14,019 Accrued professional fees 7,578 6,794 Accrued BioMarin royalties 3,695 2,846 Accrued collaboration cost sharing 2,699 — Accrued interest expense 1,251 1,291 Accrued research costs 729 401 Accrued income taxes 523 943 Accrued property and equipment 289 2,525 Other 1,408 2,484 Total accrued expenses $ 72,477 $ 68,982

INDEBTEDNESS

INDEBTEDNESS	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
INDEBTEDNESS	10. INDEBTEDNESS 2024 Convertible Notes In November 2017, the Company issued $570.0 million senior notes due on November 15, 2024 (the “2024 Notes”). The 2024 Notes were issued at face value and bear interest at the rate of 1.50% per annum, payable semi-annually in cash on each May 15 and November 15, commencing on May 15, 2018. Upon conversion, the Company may pay cash, shares of its common stock or a combination of cash and stock, as determined by the Company in its discretion. The 2024 Notes may be convertible into 7,763,552 shares of the Company’s common stock under certain circumstances prior to maturity at a conversion rate of 13.621 shares per $1,000 principal amount of the 2024 Notes, which represents a conversion price of $73.42 per share. The Company recorded a total debt discount of $171.8 million upon issuance of the 2024 Notes, consisting of an equity component of $161.2 million and debt issuance costs of $10.6 million. The debt discount is being amortized under the effective interest method and recorded as additional non-cash interest expense over the life of the 2024 Notes. The effective interest rate on the liability component of the 2024 Notes for the year ended December 31, 2017 was 6.9%. The fair value of the 2024 Notes is $1.1 billion as of June 30, 2018. It is based on open market trades and is classified as level 1 in the fair value hierarchy. Term Loan In July 2017, the Company entered into an amended and restated credit agreement (the “Amended and Restated Credit and Security Agreement”) which provides a term loan (“July 2017 Term Loan”) of $60.0 million with MidCap Financial Trust (“MidCap”). Borrowings under the Amended and Restated Credit and Security Agreement bear interest at a rate per annum equal to 6.25%, plus the one-month London Interbank Offered Rate (“LIBOR”). Commencing on July 1, 2018, and continuing for the remaining thirty six months of the facility, the Company will be required to make monthly principal payments of approximately $0.8 million, Revolving Line of Credit In July 2017, the Company entered into a revolving credit and security agreement (the “Revolving Credit Agreement”) which provides an aggregate revolving loan commitment of $40.0 million (which may be increased by an additional tranche of $20.0 million) with MidCap. Borrowings under the Revolving Credit Agreement bear interest at a rate of 3.95%, plus the one-month LIBOR. In addition to paying interest on the outstanding principal under the Revolving Credit Agreement, the Company paid $0.2 million of origination fee, which was 0.50% of the amount of the revolving loan. The Company recognized this origination fee as an other asset and it is being amortized to interest expense over the term of the line-of-credit. Additionally, the Company is liable for unused line fees, minimum balance fees, collateral fees, deferred revolving loan original fees, etc. This facility matures in July 2021. As of June 30, 2018, the Company recorded approximately $9.5 million as current portion of long-term debt and approximately $429.9 million as long-term debt on the unaudited condensed consolidated balance sheets related to the 2024 Notes, the July 2017 Term Loan, and the Revolving Credit Agreement. The following table summarizes the Company’s debt facilities for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousand) Par value of the 2024 Notes 570,000 570,000 Unamortized discount - equity component (149,710 ) (158,890 ) Unamortized discount - debt issuance costs (9,847 ) (10,450 ) Net carrying value of convertible debt 410,443 400,660 Other debt facilities 28,996 30,391 Net carrying value of total debt facilities 439,439 431,051 For the three months and six months ended June 30, 2018, the Company recorded $8.1 million and $15.8 million in interest expense, respectively. For the three months and six months ended June 30, 2017, the Company recorded $0.3 million and $0.5 in interest expense, respectively.

RESTRUCTURING

RESTRUCTURING	6 Months Ended
	Jun. 30, 2018
Restructuring And Related Activities [Abstract]
RESTRUCTURING	11. RESTRUCTURING In March 2016, the Company announced a long-term plan to consolidate all of the Company’s operations to Massachusetts as part of a strategic plan to increase operational efficiency. As part of the consolidation, research activities and some employees transitioned to the Company’s facilities in Andover and Cambridge, Massachusetts. As of December 31, 2017, the relocations and terminations were completed. The second floor and the first floor of the Corvallis facility were vacated and closed and made available for sub-leasing in December 2016 and April 2017, respectively. Using a discounted cash flow methodology and based on monthly rent payments as well as estimated sublease income, the Company recognized a total of approximately $1.5 million and $2.3 million in restructuring expenses for the second and the first floor, respectively. During the three month period ended June 30, 2018, the Corvallis facility was sold, and the Company entered into a rental termination agreement with the new landlord regarding the space made available for sub-lease. As a result, we relieved the remaining $2.2 million of cease-use liability related to this space in June 2018, which was recorded as a reduction to selling, general and administrative expenses. The following table summarizes the restructuring reserve for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Restructuring reserve beginning balance $ 2,933 $ 1,588 Restructuring expenses incurred during the period — 3,020 Amounts paid during the period (711 ) (1,675 ) Reversal of cease-use liability (2,222 ) — Restructuring reserve ending balance $ — $ 2,933

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
STOCK-BASED COMPENSATION	12. STOCK-BASED COMPENSATION The following table summarizes the Company’s stock awards granted for each of the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Stock options 528,096 $ 45.45 3,579,467 $ 13.64 1,652,681 $ 37.71 4,456,959 $ 14.16 Restricted stock units 18,695 $ 95.38 20,000 $ 36.26 169,420 $ 74.09 181,029 $ 33.03 Restricted stock awards — $ — 335,000 $ 34.65 17,090 $ 71.45 341,500 $ 34.58 Stock-based Compensation Expense For the three months ended June 30, 2018 and 2017, total stock-based compensation expense was $15.3 million and $10.5 million, respectively. For the six months ended June 30, 2018 and 2017, total stock-based compensation expense was $25.8 million and $16.2 million, respectively. The increase in stock-based compensation expense for both the three and the six months was partially driven by the achievement of a milestone related to the September 2016 restricted stock awards with performance conditions. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Research and development $ 5,029 $ 2,195 $ 7,089 $ 4,069 Selling, general and administrative 10,250 8,270 18,716 12,108 Total stock-based compensation expense $ 15,279 $ 10,465 $ 25,805 $ 16,177 The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Stock options $ 9,382 $ 6,763 $ 18,355 $ 11,801 Restricted stock awards/units 5,407 3,250 6,667 3,454 Employee stock purchase plan 490 452 783 922 Total stock-based compensation expense $ 15,279 $ 10,465 $ 25,805 $ 16,177

OTHER INCOME AND LOSS

OTHER INCOME AND LOSS	6 Months Ended
	Jun. 30, 2018
Other Income And Expenses [Abstract]
OTHER INCOME AND LOSS	13. OTHER INCOME AND LOSS The following table summarizes other income and loss for the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousand) Interest expense $ (8,145 ) $ (265 ) $ (15,779 ) $ (523 ) Interest income 1,887 189 3,759 375 Amortization of investment discount 1,569 160 2,828 260 Other (expense) income (529 ) 100 (511 ) 407 Gain from sale of Priority Review Voucher — — — 125,000 Total other (loss) income $ (5,218 ) $ 184 $ (9,703 ) $ 125,519

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	14. INCOME TAXES The Company’s tax provision for interim periods is determined using an estimate of its annual effective tax rate, adjusted for discrete items arising in that quarter. In each quarter, the Company updates its estimate of the annual effective tax rate, and if the estimated annual tax rate changes, the Company makes a cumulative adjustment in that quarter. Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Based upon the Company's history of operating losses and the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets. There was no significant income tax provision or benefit recorded for the three and six months ended June 30, 2018.

NET (LOSS) EARNINGS PER SHARE

NET (LOSS) EARNINGS PER SHARE	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
NET (LOSS) EARNINGS PER SHARE	15. NET (LOSS) EARNINGS PER SHARE Basic net (loss) earnings per share is computed by dividing net (loss) income by the weighted-average number of shares of common stock outstanding. Diluted net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding. For the three months ended June 30, 2018 and 2017, as well as for the three months ended June 30, 2017, there were no differences between basic and diluted net loss per share since the effect of common stock equivalents would be anti-dilutive due to the net loss position and, therefore, would be excluded from the diluted net loss per share calculation. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands, except per share amounts) Net (loss) income $ (109,267 ) $ (63,046 ) $ (144,630 ) $ 21,044 Weighted-average number of shares of common stock and common stock equivalents outstanding: Weighted-average number of shares of common stock outstanding for computing basic (loss) earnings per share 65,484 54,976 65,060 54,913 Dilutive effect of outstanding stock awards and stock options after application of the treasury stock method* — — — 1,263 Weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for computing diluted loss per share 65,484 54,976 65,060 56,176 Net (loss) earnings per share - basic and diluted Basic (loss) earnings per share $ (1.67 ) $ (1.15 ) $ (2.22 ) $ 0.38 Diluted (loss) earnings per share $ (1.67 ) $ (1.15 ) $ (2.22 ) $ 0.37 * For the three and six months ended June 30, 2018, stock options, RSAs, RSUs, stock appreciation rights (“SAR”) to purchase 9.4 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive. For the three months ended June 30, 2017, stock options, RSAs and SARs to purchase 10.1 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive. For the six months ended June 30, 2017, out of money stock options, unvested performance-based RSUs and RSAs whose performance milestones were not achieved and potentially issuable common stock for ESPP to purchase approximately 7.0 million shares of the Company’s common stock were excluded from the net earnings per share calculation as their effect would have been anti-dilutive.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	16. COMMITMENTS AND CONTINGENCIES Lease Obligations In April 2018, the Company entered into the seventh amendment to its Cambridge, Massachusetts headquarters lease which extended the original term of the lease to September 30, 2025 and increased the total rental space by approximately 63,698 square feet. The following table summarizes the aggregate non-cancelable future minimum payments under the Company’s leases: As of June 30, 2018 (in thousands) 2018 (July - December) $ 3,277 2019 7,343 2020 7,401 2021 8,574 2022 8,862 Thereafter 25,328 Total minimum lease payments $ 60,785 Manufacturing Obligations The Company has entered into long-term contractual arrangements from time to time for the provision of goods and services. In addition to contract manufacturing agreements already in place, in June 2018, the Company entered into the Brammer Manufacturing Agreement with Brammer. Please see Note 3, Collaboration, License, and Manufacturing Agreements, The following table summarizes the aggregate non-cancelable contractual obligations arising from our manufacturing obligations: As of June 30, 2018 (in thousands) 2018 (July - December) $ 68,824 2019 64,676 2020 45,939 2021 32,000 2022 40,000 Thereafter 160,000 Total manufacturing commitments $ 411,439 Litigation In the normal course of business, the Company may from time to time be named as a party to various legal claims, actions and complaints, including matters involving securities, employment, intellectual property, effects from the use of therapeutics utilizing its technology, or others. For example, purported class action complaints were filed against the Company and certain of its officers in the U.S. District Court for the District of Massachusetts on January 27, 2014 and January 29, 2014. The complaints were consolidated into a single action ( Corban v. Sarepta, et. al., No. 14-cv-10201 En Banc Another complaint was filed in the U.S. District Court for the District of Massachusetts on December 3, 2014 styled William Kader, Individually and on Behalf of All Others Similarly Situated v. Sarepta Therapeutics Inc., Christopher Garabedian, and Sandesh Mahatme ( Kader v. Sarepta et.al 1:14-cv-14318 On February 5, 2015, a derivative suit was filed in the 215th Judicial District of Harris County, Texas against the Company’s Board of Directors ( David Smith, derivatively on behalf of Sarepta Therapeutics, Inc., v. Christopher Garabedian et al., No. 2015-06645 On March 16, 2016, a derivative suit was filed in the U.S. District Court for the District of Massachusetts against the Company’s Board of Directors ( Dawn Cherry, on behalf of nominal defendant Sarepta Therapeutics, Inc., v. Behrens et al., No. 16-cv-10531 Additionally, on September 23, 2014, a derivative suit was filed against the Company’s Board of Directors with the Court of Chancery of the State of Delaware ( Terry McDonald, derivatively on behalf of Sarepta Therapeutics, Inc., et al. v. Goolsbee et al., No. 10157

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	17. SUBSEQUENT EVENTS In August 2018, the Company entered into a License, Development and Option Agreement (the “License Agreement”) and an Equity Investment Agreement with Lacerta Therapeutics, Inc. (“Lacerta”). The Company will in-license one of Lacerta’s preclinical programs (the “License”) and has options to in-license additional programs (the “Options”) for additional consideration. In connection with the closing of these transactions, the Company will make an equity investment of $30 million and an up-front payment of $8 million to Lacerta in consideration of the License and the Options. Under the License Agreement, the Company may be liable for additional payments relating to development and commercialization milestones and a high single digit royalty upon commercialization of the product. If the Company decides to exercise the Options to in-license additional programs, it may be liable for additional payments relating to development and commercialization milestones and tiered high single digit royalties upon commercialization of the products.

SUMMARY OF SIGNIFICANT ACCOUN23

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), reflect the accounts of Sarepta Therapeutics, Inc. and its wholly-owned subsidiaries. All intercompany transactions between and among its consolidated subsidiaries have been eliminated. Management has determined that the Company operates in one segment: discovering, developing, manufacturing and delivering therapies to patients with DMD. The Company’s CEO, as the chief operating decision-maker, manages and allocates resources to the operations of the Company on a total company basis. The Company’s research and development organization is responsible for the research and discovery of new product candidates and supports development and registration efforts for potential future products. The Company’s supply chain organization manages the development of the manufacturing processes, clinical trial supply and commercial product supply. The Company’s commercial organization is responsible for commercialization of EXONDYS 51 in the U.S. and internationally. The Company is supported by other back-office general and administration functions. Consistent with this decision-making process, the Company’s CEO uses consolidated, single-segment financial information for purposes of evaluating performance, forecasting future period financial results, allocating resources and setting incentive targets.
Estimates and Uncertainties	Estimates and Uncertainties The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include revenue recognition, inventory, convertible debt, valuation of stock-based awards, research and development expenses and income tax.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist of accounts receivable from customers and cash, cash equivalents and investments held at financial institutions. As of June 30, 2018, the majority of the Company’s accounts receivable arose from product sales in the U.S. and all customers have standard payment terms which generally require payment within 30 to 60 days. Outside of the U.S., the payment terms range between 45 and 120 days. Three individual customers accounted for 44%, 35% and 19% of net product revenues for the six months ended June 30, 2018 and 61%, 26% and 11% of accounts receivable from product sales as of June 30, 2018. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in the customers’ credit profile. As of June 30, 2018, the Company believes that such customers are of high credit quality. As of June 30, 2018 the Company’s cash equivalents and investments were concentrated at a single financial institution, which potentially exposes the Company to credit risks. However, the Company does not believe that there is significant risk of non-performance by the financial institution.
Revenue Recognition	The Company has adopted Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“ASC 606”) effective as of January 1, 2018. The Company has chosen to use the full retrospective transition method, under which it is required to revise its consolidated financial statements for the years ended December 31, 2016 and 2017 as well as any applicable interim periods within those years, as if ASC 606 had been effective for those periods. Under ASC 606, the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (1) identify the contracts with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied. For all contracts that fall into the scope of ASC 606, only one performance obligation has been identified by the Company: to timely deliver drug products to the customer’s designated warehouses. Product Revenues The Company distributes its product principally through a limited number of specialty distributor and specialty pharmacies in the U.S. and certain distributors in the European Union (“EU”), Israel and Middle East (collectively, “Customers”). The Customers subsequently resell the product to patients and health care providers. The Company provides no right of return to the Customers except in cases of shipping error or product defect. Product revenues are recognized when the Customers take control of the product, which typically occurs upon delivery to the Customers. For both the three and six months ended June 30, 2018, the majority of the revenues recognized were generated by the specialty distributor and specialty pharmacies in the U.S. Variable Consideration Product revenues are recorded at the net sales price (“transaction price”) which includes estimated reserves for variable consideration, such as Medicaid rebates, governmental chargebacks, including Public Health Service (“PHS”) chargebacks, prompt payment discounts, co-pay assistance and distribution fees. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if no payment is required by the Company) or a current liability (if a payment is required by the Company). These reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contracts. Additional details relating to variable consideration follows: • Medicaid rebates relate to the Company’s estimated obligations to states under established reimbursement arrangements. Rebate reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability which is included in accrued expenses. • Governmental chargebacks, including PHS chargebacks, relate to the Company’s estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices that the Company charges to wholesalers. The wholesaler charges the Company for the difference between what the wholesaler pays for the products and the ultimate selling price to the qualified healthcare providers. Chargeback reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider from the wholesaler, and the Company generally issues credits for such amounts within a few weeks of receiving notification of resale from the wholesaler. • Prompt payment discounts relate to the Company’s estimated obligations for credits to be granted to a specialty pharmacy for remitting payment on its purchases within established incentive periods. Reserves for prompt payment discounts are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. • Co-pay assistance relates to financial assistance provided to qualified patients, whereby the Company may assist them with prescription drug co-payments required by the patient’s insurance provider. Reserves for co-pay assistance are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability which is included in accrued expenses. • Distribution fees relate to fees paid to Customers in the distribution channel that provide the Company with inventory management, data and distribution services and are generally accounted for as a reduction of revenue. To the extent that the services received are distinct from the Company’s sale of products to the Customer, these payments are accounted for as selling, general and administrative expenses. The impact of adopting ASC 606 was not material. There have not been any other material changes to the Company’s accounting policies as of June 30, 2018.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, “ Leases (Topic 842) Leases In March 2017, the FASB issued ASU No. 2017-08, “ Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In June 2018, the FASB issued ASU 2018-07, “ Compensation - Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Assets Measured and Carried at Fair Value	The tables below present information about the Company’s financial assets that are measured and carried at fair value and indicate the level within the fair value hierarchy of valuation techniques it utilizes to determine such fair value: Fair Value Measurement as of June 30, 2018 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 211,197 $ 211,197 $ — $ — Commercial paper 189,622 — 189,622 — Government and government agency bonds 278,512 278,512 — — Corporate bonds 85,594 85,594 — — Certificates of deposit $ 1,001 1,001 — — Total $ 765,926 $ 576,304 $ 189,622 $ — Fair Value Measurement as of December 31, 2017 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 352,370 $ 352,370 $ — $ — Commercial paper 133,368 — 133,368 — Government and government agency bonds 294,717 284,745 9,972 — Corporate bonds 127,956 127,956 — — Certificates of deposit 648 648 — — Total $ 909,059 $ 765,719 $ 143,340 $ —

CASH, CASH EQUIVALENTS AND MA25

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Tables)	6 Months Ended
	Jun. 30, 2018
Cash And Cash Equivalents [Abstract]
Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents	The following table summarizes the Company’s financial assets with maturities of less than 90 days from the date of purchase included in cash equivalents in the unaudited condensed consolidated balance sheets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Money market funds $ 211,197 $ 352,370 Corporate bonds 14,959 16,720 Government and government agency bonds — 49,972 Total $ 226,156 $ 419,062
Summary of Company Cash, Cash Equivalents and Short-Term Investments	The following tables summarize the Company’s cash, cash equivalents and short-term investments for each of the periods indicated: As of June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value (in thousands) Cash and money market funds $ 395,416 $ — $ — 395,416 Commercial paper 189,622 — — 189,622 Government and government agency bonds 278,680 5 (173 ) 278,512 Corporate bonds 85,787 — (193 ) 85,594 Total $ 949,505 $ 5 $ (366 ) 949,144 As reported: Cash and cash equivalents $ 410,375 $ — $ — 410,375 Short-term investments 539,130 5 (366 ) 538,769 Total $ 949,505 $ 5 $ (366 ) 949,144 As of December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value (in thousands) Cash and money market funds $ 532,999 $ — $ — $ 532,999 Commercial paper - current 133,368 — — 133,368 Government and government agency bonds - current 294,915 2 (200 ) 294,717 Corporate bonds Current 118,121 — (145 ) 117,976 Non-current 10,016 — (36 ) 9,980 Total $ 1,089,419 $ 2 $ (381 ) $ 1,089,040 As reported: Cash and cash equivalents $ 599,698 $ 2 $ (9 ) $ 599,691 Short-term investments 479,705 — (336 ) 479,369 Long-term investments 10,016 — (36 ) 9,980 Total $ 1,089,419 $ 2 $ (381 ) $ 1,089,040

ACCOUNTS RECEIVABLE AND RESER26

ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES (Tables)	6 Months Ended
	Jun. 30, 2018
Receivables Net Current [Abstract]
Summary of Components of Accounts Receivable	The following table summarizes the components of the Company’s accounts receivable for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Product sales, net of discounts and allowances $ 42,056 $ 28,539 Government contract receivables 929 929 Total accounts receivable $ 42,985 $ 29,468
Summary of Change in Reserves for Discounts and Allowances	The following table summarizes an analysis of the change in reserves for discounts and allowances for the periods indicated: Chargebacks Rebates Prompt Pay Other Total (in thousands) Balance, as of December 31, 2017 $ 995 $ 6,959 $ 169 $ 464 $ 8,587 Provision 6,490 11,178 1,094 2,460 21,222 Payments/credits (6,622 ) (1,978 ) (917 ) (1,813 ) (11,330 ) Balance, as of June 30, 2018 $ 863 $ 16,159 $ 346 $ 1,111 $ 18,479
Summary of Total Reserves Included in Consolidated Balance Sheets	The following table summarizes the total reserves above included in the Company’s unaudited condensed consolidated balance sheets for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Reduction to accounts receivable $ 1,612 $ 1,285 Component of accrued expenses 16,867 7,302 Total reserves $ 18,479 $ 8,587

INVENTORY (Tables)

INVENTORY (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Summary of Components of Inventory	The following table summarizes the components of the Company’s inventory for the period indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Raw materials $ 64,525 $ 53,875 Work in progress 37,107 27,442 Finished goods 2,494 2,288 Total inventory $ 104,126 $ 83,605

OTHER CURRENT ASSETS AND OTHE28

OTHER CURRENT ASSETS AND OTHER NON-CURRENT ASSETS (Tables)	6 Months Ended
	Jun. 30, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Summary of Other Current Assets	The following table summarizes the Company’s other current assets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Manufacturing-related deposits and prepaids $ 15,338 $ 18,650 Leasehold improvement receivable 10,409 — Prepaid clinical and preclinical expenses 7,286 5,175 Prepaid maintenance and license fees 2,745 1,711 Prepaid research expenses 2,472 2,896 Prepaid commercial expenses 374 1,589 Asset held for sale — 1,501 Other prepaids 2,497 2,726 Other 1,868 2,263 Total other current assets $ 42,989 $ 36,511
Summary of Other Non-current Assets	The following table summarizes the Company’s other non-current assets for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Manufacturing-related deposits $ 22,633 $ — Prepaid clinical expenses 8,680 7,488 Alternative minimum tax credit 2,881 3,315 Restricted investment 1,001 784 Long-term available-for-sale securities — 9,980 Other 240 242 Total other non-current assets $ 35,435 $ 21,809

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	6 Months Ended
	Jun. 30, 2018
Payables And Accruals [Abstract]
Summary of Accrued Expenses	The following table summarizes the Company’s accrued expenses for each of the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Accrued employee compensation costs $ 17,949 $ 14,402 Product revenue related reserves 16,867 7,302 Accrued clinical and preclinical costs 11,068 15,975 Accrued contract manufacturing costs 8,421 14,019 Accrued professional fees 7,578 6,794 Accrued BioMarin royalties 3,695 2,846 Accrued collaboration cost sharing 2,699 — Accrued interest expense 1,251 1,291 Accrued research costs 729 401 Accrued income taxes 523 943 Accrued property and equipment 289 2,525 Other 1,408 2,484 Total accrued expenses $ 72,477 $ 68,982

INDEBTEDNESS (Tables)

INDEBTEDNESS (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Summary of Debt Facilities	As of June 30, 2018, the Company recorded approximately $9.5 million as current portion of long-term debt and approximately $429.9 million as long-term debt on the unaudited condensed consolidated balance sheets related to the 2024 Notes, the July 2017 Term Loan, and the Revolving Credit Agreement. The following table summarizes the Company’s debt facilities for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousand) Par value of the 2024 Notes 570,000 570,000 Unamortized discount - equity component (149,710 ) (158,890 ) Unamortized discount - debt issuance costs (9,847 ) (10,450 ) Net carrying value of convertible debt 410,443 400,660 Other debt facilities 28,996 30,391 Net carrying value of total debt facilities 439,439 431,051

RESTRUCTURING (Tables)

RESTRUCTURING (Tables)	6 Months Ended
	Jun. 30, 2018
Restructuring And Related Activities [Abstract]
Summary of Restructuring Reserve	The following table summarizes the restructuring reserve for the periods indicated: As of June 30, 2018 As of December 31, 2017 (in thousands) Restructuring reserve beginning balance $ 2,933 $ 1,588 Restructuring expenses incurred during the period — 3,020 Amounts paid during the period (711 ) (1,675 ) Reversal of cease-use liability (2,222 ) — Restructuring reserve ending balance $ — $ 2,933

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Awards Granted	The following table summarizes the Company’s stock awards granted for each of the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Grants Weighted Average Grant Date Fair Value Stock options 528,096 $ 45.45 3,579,467 $ 13.64 1,652,681 $ 37.71 4,456,959 $ 14.16 Restricted stock units 18,695 $ 95.38 20,000 $ 36.26 169,420 $ 74.09 181,029 $ 33.03 Restricted stock awards — $ — 335,000 $ 34.65 17,090 $ 71.45 341,500 $ 34.58
Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statements of Operations and Comprehensive Loss	The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Research and development $ 5,029 $ 2,195 $ 7,089 $ 4,069 Selling, general and administrative 10,250 8,270 18,716 12,108 Total stock-based compensation expense $ 15,279 $ 10,465 $ 25,805 $ 16,177
Summary of Stock-Based Compensation Expense by Grant Type Included within Condensed Consolidated Statements of Operations and Comprehensive Loss	The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands) Stock options $ 9,382 $ 6,763 $ 18,355 $ 11,801 Restricted stock awards/units 5,407 3,250 6,667 3,454 Employee stock purchase plan 490 452 783 922 Total stock-based compensation expense $ 15,279 $ 10,465 $ 25,805 $ 16,177

OTHER INCOME AND LOSS (Tables)

OTHER INCOME AND LOSS (Tables)	6 Months Ended
	Jun. 30, 2018
Other Income And Expenses [Abstract]
Summary of Other Income and Loss	The following table summarizes other income and loss for the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousand) Interest expense $ (8,145 ) $ (265 ) $ (15,779 ) $ (523 ) Interest income 1,887 189 3,759 375 Amortization of investment discount 1,569 160 2,828 260 Other (expense) income (529 ) 100 (511 ) 407 Gain from sale of Priority Review Voucher — — — 125,000 Total other (loss) income $ (5,218 ) $ 184 $ (9,703 ) $ 125,519

NET (LOSS) EARNINGS PER SHARE (

NET (LOSS) EARNINGS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Basic and Diluted Net (Loss) Earnings Per Share	For the three months ended June 30, 2018 and 2017, as well as for the three months ended June 30, 2017, there were no differences between basic and diluted net loss per share since the effect of common stock equivalents would be anti-dilutive due to the net loss position and, therefore, would be excluded from the diluted net loss per share calculation. For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (in thousands, except per share amounts) Net (loss) income $ (109,267 ) $ (63,046 ) $ (144,630 ) $ 21,044 Weighted-average number of shares of common stock and common stock equivalents outstanding: Weighted-average number of shares of common stock outstanding for computing basic (loss) earnings per share 65,484 54,976 65,060 54,913 Dilutive effect of outstanding stock awards and stock options after application of the treasury stock method* — — — 1,263 Weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for computing diluted loss per share 65,484 54,976 65,060 56,176 Net (loss) earnings per share - basic and diluted Basic (loss) earnings per share $ (1.67 ) $ (1.15 ) $ (2.22 ) $ 0.38 Diluted (loss) earnings per share $ (1.67 ) $ (1.15 ) $ (2.22 ) $ 0.37 * For the three and six months ended June 30, 2018, stock options, RSAs, RSUs, stock appreciation rights (“SAR”) to purchase 9.4 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive. For the three months ended June 30, 2017, stock options, RSAs and SARs to purchase 10.1 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive. For the six months ended June 30, 2017, out of money stock options, unvested performance-based RSUs and RSAs whose performance milestones were not achieved and potentially issuable common stock for ESPP to purchase approximately 7.0 million shares of the Company’s common stock were excluded from the net earnings per share calculation as their effect would have been anti-dilutive.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Summary of Aggregate Non-Cancelable Future Minimum Payments under Company's Leases	The following table summarizes the aggregate non-cancelable future minimum payments under the Company’s leases: As of June 30, 2018 (in thousands) 2018 (July - December) $ 3,277 2019 7,343 2020 7,401 2021 8,574 2022 8,862 Thereafter 25,328 Total minimum lease payments $ 60,785
Summary of Aggregate Non-Cancelable Contractual Obligations Arising from Manufacturing Obligations	The following table summarizes the aggregate non-cancelable contractual obligations arising from our manufacturing obligations: As of June 30, 2018 (in thousands) 2018 (July - December) $ 68,824 2019 64,676 2020 45,939 2021 32,000 2022 40,000 Thereafter 160,000 Total manufacturing commitments $ 411,439

Organization and Nature of Bu36

Organization and Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash, cash equivalents and investments	$ 950,200
Cash and cash equivalents	410,375	$ 599,691	$ 168,348
Short-term investments	538,769	479,369
Restricted investment	$ 1,001	$ 784

Summary of Significant Accoun37

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018Segment
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments	1
Product Revenues [Member] | Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	44.00%
Product Revenues [Member] | Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	35.00%
Product Revenues [Member] | Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	19.00%
Accounts Receivable [Member] | Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	61.00%
Accounts Receivable [Member] | Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	26.00%
Accounts Receivable [Member] | Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	11.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term	30 days
Minimum [Member] | Outside of U.S. [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term	45 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term	60 days
Maximum [Member] | Outside of U.S. [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term	120 days

Collaboration, License and Ma38

Collaboration, License and Manufacturing Agreements - Additional Information (Detail)	1 Months Ended		3 Months Ended			6 Months Ended
	Jun. 30, 2018USD ($)PaymentMonthQuarter	May 31, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)
Warrant Agreement [Member] | Myonexus Therapeutics, Inc. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front cash payment under agreements		$ 60,000,000
Development milestone payments evaluation period		2 years
Up-front payment					$ 60,000,000	$ 60,000,000
Development milestone payments					45,000,000
Warrant Agreement [Member] | Myonexus Therapeutics, Inc. [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional development milestone payments to be paid		$ 45,000,000
Manufacturing Agreement [Member] | Brammer [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Advance upfront fee to be paid on execution of agreements	$ 20,000,000				20,000,000	$ 20,000,000
Number of non-refundable process equipment fee payments | Payment	2
Quarterly capacity access fee payment	$ 10,000,000
Portion of advance payment applied as credit to quarterly capacity access fees						one-tenth
Quarterly capacity access fees due and payable beginning date	Jul. 1, 2019
Quarterly capacity access fees due and payable ending date	Dec. 31, 2021
Net capacity access fee	$ 8,000,000
Manufacturing agreement term	6 years
Successive renewal term of manufacturing agreement	2 years
Maximum number of months prior to expiration of term for renewal | Month	24
Maximum additional quarters of remittance of capacity access fees required to terminate agreement | Quarter	8
Manufacturing Agreement [Member] | Brammer [Member] | Other Non-current Asset [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Advance upfront fee to be paid on execution of agreements	$ 20,000,000				20,000,000	$ 20,000,000
Manufacturing Agreement [Member] | Brammer [Member] | Other Asset [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Process equipment fee payments capitalized as other asset	$ 5,000,000				$ 5,000,000	$ 5,000,000
Manufacturing Agreement [Member] | Brammer [Member] | Scenario Forecast [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable process equipment fee payments			$ 5,000,000	$ 5,000,000

Assets Measured and Carried at

Assets Measured and Carried at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 765,926	$ 909,059
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	211,197	352,370
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	189,622	133,368
Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	278,512	294,717
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	85,594	127,956
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,001	648
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	576,304	765,719
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	211,197	352,370
Level 1 [Member] | Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	278,512	284,745
Level 1 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	85,594	127,956
Level 1 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,001	648
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	189,622	143,340
Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 189,622	133,368
Level 2 [Member] | Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		$ 9,972

Summary of Company Financial As

Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 226,156	$ 419,062
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	211,197	352,370
Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 14,959	16,720
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents		$ 49,972

Cash, Cash Equivalents and Ma41

Cash, Cash Equivalents and Marketable Securities - Additional Information (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Weighted average maturity period of available-for-sale securities	2 months	7 months

Summary of Company Cash, Cash E

Summary of Company Cash, Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	$ 949,505	$ 1,089,419
Cash, cash equivalents and short-term investments, Gross unrealized gains	5	2
Cash, cash equivalents and short-term investments, Gross unrealized losses	(366)	(381)
Cash, cash equivalents and short-term investments, Fair market value	949,144	1,089,040
Cash and Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	395,416	532,999
Cash, cash equivalents and short-term investments, Fair market value	395,416	532,999
Commercial Paper [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	189,622	133,368
Cash, cash equivalents and short-term investments, Fair market value	189,622	133,368
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	278,680	294,915
Cash, cash equivalents and short-term investments, Gross unrealized gains	5	2
Cash, cash equivalents and short-term investments, Gross unrealized losses	(173)	(200)
Cash, cash equivalents and short-term investments, Fair market value	278,512	294,717
Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	85,787
Cash, cash equivalents and short-term investments, Gross unrealized losses	(193)
Cash, cash equivalents and short-term investments, Fair market value	85,594
Cash and Cash Equivalents [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	410,375	599,698
Cash, cash equivalents and short-term investments, Gross unrealized gains		2
Cash, cash equivalents and short-term investments, Gross unrealized losses		(9)
Cash, cash equivalents and short-term investments, Fair market value	410,375	599,691
Short-term Investments [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	539,130	479,705
Cash, cash equivalents and short-term investments, Gross unrealized gains	5
Cash, cash equivalents and short-term investments, Gross unrealized losses	(366)	(336)
Cash, cash equivalents and short-term investments, Fair market value	$ 538,769	479,369
Corporate Bonds - Current [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost		118,121
Cash, cash equivalents and short-term investments, Gross unrealized losses		(145)
Cash, cash equivalents and short-term investments, Fair market value		117,976
Corporate Bonds - Non-current [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost		10,016
Cash, cash equivalents and short-term investments, Gross unrealized losses		(36)
Cash, cash equivalents and short-term investments, Fair market value		9,980
Long-term Investments [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost		10,016
Cash, cash equivalents and short-term investments, Gross unrealized losses		(36)
Cash, cash equivalents and short-term investments, Fair market value		$ 9,980

Summary of Components of Accoun

Summary of Components of Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Receivables Net Current [Abstract]
Product sales, net of discounts and allowances	$ 42,056	$ 28,539
Government contract receivables	929	929
Total accounts receivable	$ 42,985	$ 29,468

Summary of Change in Reserves f

Summary of Change in Reserves for Discounts and Allowances (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2017	$ 8,587
Provision	21,222
Payments/credits	(11,330)
Balance, as of June 30, 2018	18,479
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2017	995
Provision	6,490
Payments/credits	(6,622)
Balance, as of June 30, 2018	863
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2017	6,959
Provision	11,178
Payments/credits	(1,978)
Balance, as of June 30, 2018	16,159
Prompt Pay [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2017	169
Provision	1,094
Payments/credits	(917)
Balance, as of June 30, 2018	346
Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2017	464
Provision	2,460
Payments/credits	(1,813)
Balance, as of June 30, 2018	$ 1,111

Summary of Total Reserves Inclu

Summary of Total Reserves Included in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Receivables Net Current [Abstract]
Reduction to accounts receivable	$ 1,612	$ 1,285
Component of accrued expenses	16,867	7,302
Total reserves	$ 18,479	$ 8,587

Inventory - Summary of Componen

Inventory - Summary of Components of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 64,525	$ 53,875
Work in progress	37,107	27,442
Finished goods	2,494	2,288
Total inventory	$ 104,126	$ 83,605

Summary of Other Current Assets

Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 15,338	$ 18,650
Leasehold improvement receivable	10,409
Prepaid clinical and preclinical expenses	7,286	5,175
Prepaid maintenance and license fees	2,745	1,711
Prepaid research expenses	2,472	2,896
Prepaid commercial expenses	374	1,589
Asset held for sale		1,501
Other prepaids	2,497	2,726
Other	1,868	2,263
Total other current assets	$ 42,989	$ 36,511

Summary of Other Non-current As

Summary of Other Non-current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Prepaid Expense And Other Assets Noncurrent [Abstract]
Manufacturing-related deposits	$ 22,633
Prepaid clinical expenses	8,680	$ 7,488
Alternative minimum tax credit	2,881	3,315
Restricted investment	1,001	784
Long-term available-for-sale securities		9,980
Other	240	242
Total other non-current assets	$ 35,435	$ 21,809

Summary of Accrued Expenses (De

Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued employee compensation costs	$ 17,949	$ 14,402
Product revenue related reserves	16,867	7,302
Accrued clinical and preclinical costs	11,068	15,975
Accrued contract manufacturing costs	8,421	14,019
Accrued professional fees	7,578	6,794
Accrued BioMarin royalties	3,695	2,846
Accrued collaboration cost sharing	2,699
Accrued interest expense	1,251	1,291
Accrued research costs	729	401
Accrued income taxes	523	943
Accrued property and equipment	289	2,525
Other	1,408	2,484
Total accrued expenses	$ 72,477	$ 68,982

Indebtedness - Additional Infor

Indebtedness - Additional Information (Detail)	1 Months Ended		3 Months Ended		6 Months Ended
	Nov. 30, 2017USD ($)shares$ / shares	Jul. 31, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Long-term debt			$ 429,925,000		$ 429,925,000		$ 424,876,000
2024 Notes, The July 2017 Term Loan, and The Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Current portion of long-term debt			9,500,000		9,500,000
Long-term debt			429,900,000		429,900,000
Interest expense related to debt facilities			8,100,000	$ 300,000	15,800,000	$ 500,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 570,000,000		570,000,000		$ 570,000,000		570,000,000
Debt instrument, maturity date	Nov. 15, 2024
Debt instrument, interest rate per annum	1.50%
Debt instrument, payment frequency					The 2024 Notes were issued at face value and bear interest at the rate of 1.50% per annum, payable semi-annually in cash on each May 15 and November 15, commencing on May 15, 2018.
Debt instrument, conversion rate	0.013621
Debt instrument, conversion price | $ / shares	$ 73.42
Debt discount	$ 171,800,000		149,710,000		$ 149,710,000		$ 158,890,000
Proceeds for issuance of notes recorded to equity component	161,200,000
Debt issuance costs	$ 10,600,000
Effective interest rate percentage							6.90%
2024 Convertible Notes [Member] | Level 1 [Member]
Debt Instrument [Line Items]
Debt fair value			$ 1,100,000,000		$ 1,100,000,000
2024 Convertible Notes [Member] | Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, convertible into shares | shares	7,763,552
MidCap Financial Amended and Restated Credit and Security Agreement [Member] | July 2017 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate per annum		6.25%
Current borrowing capacity		$ 60,000,000
Variable interest rate description		one-month London Interbank Offered Rate
Monthly principal payments commencement date		Jul. 1, 2018
Periodic principal payment frequency		monthly
Monthly principal payments		$ 800,000
Credit facility maturity date		2021-07
Midcap Financial Revolving Credit and Security Agreement [Member] | Revolving Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate per annum		3.95%
Current borrowing capacity		$ 40,000,000
Variable interest rate description					one-month LIBOR
Credit facility maturity date		2021-07
Line of credit facility additional tranche that may be increased		$ 20,000,000
Origination fee		$ 200,000
Origination fee, percentage		0.50%

Indebtedness - Summary of Debt

Indebtedness - Summary of Debt Facilities (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017	Nov. 30, 2017
Debt Instrument [Line Items]
Other debt facilities	$ 28,996,000	$ 30,391,000
Net carrying value of total debt facilities	439,439,000	431,051,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Par value of the 2024 Notes	570,000,000	570,000,000	$ 570,000,000
Unamortized discount - equity component	(149,710,000)	(158,890,000)	$ (171,800,000)
Unamortized discount - debt issuance costs	(9,847,000)	(10,450,000)
Net carrying value of convertible debt	$ 410,443,000	$ 400,660,000

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			6 Months Ended
	Jun. 30, 2018	Apr. 30, 2017	Dec. 31, 2016	Jun. 30, 2018
Restructuring Cost And Reserve [Line Items]
Relieved cease-use liability				$ (2,222)
Corvallis Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date				2016-03
Restructuring, completion date				Dec. 31, 2017
Corvallis Plan [Member] | Selling, General And Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Relieved cease-use liability	$ (2,200)
Corvallis Plan [Member] | Facility Closing [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses		$ 2,300	$ 1,500

Summary of Restructuring Reserv

Summary of Restructuring Reserve (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Restructuring reserve beginning balance	$ 2,933	$ 1,588
Restructuring expenses incurred during the period		3,020
Amounts paid during the period	(711)	(1,675)
Reversal of cease-use liability	$ (2,222)
Restructuring reserve ending balance		$ 2,933

Summary of Stock Awards Granted

Summary of Stock Awards Granted (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	528,096	3,579,467	1,652,681	4,456,959
Weighted Average Grant Date Fair Value, Stock options	$ 45.45	$ 13.64	$ 37.71	$ 14.16
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock units and awards	18,695	20,000	169,420	181,029
Weighted Average Grant Date Fair Value, Restricted stock units and awards	$ 95.38	$ 36.26	$ 74.09	$ 33.03
Restricted Stock Awards (RSAs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock units and awards		335,000	17,090	341,500
Weighted Average Grant Date Fair Value, Restricted stock units and awards		$ 34.65	$ 71.45	$ 34.58

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based compensation expense	$ 15,279	$ 10,465	$ 25,805	$ 16,177

Summary of Stock-Based Compensa

Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 15,279	$ 10,465	$ 25,805	$ 16,177
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,029	2,195	7,089	4,069
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 10,250	$ 8,270	$ 18,716	$ 12,108

Summary of Stock-Based Compen57

Summary of Stock-Based Compensation Expense by Grant Type Included within Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 15,279	$ 10,465	$ 25,805	$ 16,177
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	9,382	6,763	18,355	11,801
Restricted Stock Awards/Units (RSAs/RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,407	3,250	6,667	3,454
Employee Stock Purchase Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 490	$ 452	$ 783	$ 922

Summary of Other Income and Los

Summary of Other Income and Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Nonoperating Income Expense [Abstract]
Interest expense	$ (8,145)	$ (265)	$ (15,779)	$ (523)
Interest income	1,887	189	3,759	375
Amortization of investment discount	1,569	160	2,828	260
Other (expense) income	(529)	100	(511)	407
Gain from sale of Priority Review Voucher				125,000
Other (loss) income	$ (5,218)	$ 184	$ (9,703)	$ 125,519

Basic and Diluted Net (Loss) Ea

Basic and Diluted Net (Loss) Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net (loss) income		$ (109,267)	$ (63,046)	$ (144,630)	$ 21,044
Weighted-average number of shares of common stock and common stock equivalents outstanding:
Weighted-average number of shares of common stock outstanding for computing basic (loss) earnings per share		65,484	54,976	65,060	54,913
Dilutive effect of outstanding stock awards and stock options after application of the treasury stock method	[1]	0	0	0	1,263
Weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for computing diluted loss per share		65,484	54,976	65,060	56,176
Net (loss) earnings per share - basic and diluted
Basic (loss) earnings per share		$ (1.67)	$ (1.15)	$ (2.22)	$ 0.38
Diluted (loss) earnings per share		$ (1.67)	$ (1.15)	$ (2.22)	$ 0.37
[1]	For the three and six months ended June 30, 2018, stock options, RSAs, RSUs, stock appreciation rights (“SAR”) to purchase 9.4 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive.  For the three months ended June 30, 2017, stock options, RSAs and SARs to purchase 10.1 million shares of the Company’s common stock were excluded from the net loss per share calculation as their effect would have been anti-dilutive. For the six months ended June 30, 2017, out of money stock options, unvested performance-based RSUs and RSAs whose performance milestones were not achieved and potentially issuable common stock for ESPP to purchase approximately 7.0 million shares of the Company’s common stock were excluded from the net earnings per share calculation as their effect would have been anti-dilutive.

Basic and Diluted Net (Loss) 60

Basic and Diluted Net (Loss) Earnings Per Share (Parenthetical) (Detail) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Anti-dilutive securities excluded from computation of net (loss) earnings per share	9.4	10.1	9.4	7

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - Lease Agreements [Member] - Seventh Amendment [Member]	1 Months Ended
	Apr. 30, 2018ft²
Commitments And Contingencies [Line Items]
Extended original term of lease	Sep. 30, 2025
Total rental space	63,698

Summary of Aggregate Non-Cancel

Summary of Aggregate Non-Cancelable Future Minimum Payments under Company's Leases (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2018 (July - December)	$ 3,277
2,019	7,343
2,020	7,401
2,021	8,574
2,022	8,862
Thereafter	25,328
Total minimum lease payments	$ 60,785

Summary of Aggregate Non-Canc63

Summary of Aggregate Non-Cancelable Contractual Obligations Arising from Manufacturing Obligations (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2018 (July - December)	$ 68,824
2,019	64,676
2,020	45,939
2,021	32,000
2,022	40,000
Thereafter	160,000
Total manufacturing commitments	$ 411,439

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - License Agreement and Equity Investment Agreement [Member] - Subsequent Event [Member] - Lacerta Therapeutics, Inc. [Member] $ in Millions	Aug. 07, 2018USD ($)
Subsequent Event [Line Items]
Equity investment	$ 30
Up-front payment	$ 8