| Summary of Significant Accounting Policies | SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the consolidated financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, clinical trial accruals, fair value of assets and liabilities including short-term and long-term classification, embedded derivatives, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results may differ from those estimates. Liquidity and Financial Condition To date, a significant portion of the Company’s resources have been dedicated to the research and development of its products. The Company made GOCOVRI available for physician and patient use in the fourth quarter of 2017, with a full commercial launch via the deployment of the Company’s sales team in January 2018. Prior to the generation of revenue from GOCOVRI, the Company had not generated any commercial revenue from the sale of its products. Based upon the current status of, and plans for, its product development and commercialization, the Company believes that the existing cash, cash equivalents, and investments of $ 176.4 million as of December 31, 2017 , will be adequate to satisfy the Company’s capital needs through at least the next twelve months from the issuance of this annual report on Form 10-K. However, the process of developing and commercializing products requires significant research and development, preclinical testing and clinical trials, manufacturing arrangements, as well as regulatory approvals. These activities, together with the Company’s selling, general and administrative expenses, are expected to result in significant operating losses until the commercialization of the Company’s products or license agreements generate sufficient revenue to offset expenses. Under its license agreement with Allergan, the Company received the final milestone payment in 2014, and is not entitled to receive any royalties for net sales of Namzaric ® until mid-2020. Although the Company is eligible to receive royalties on net sales of Namenda XR ® in mid-2018, it does not expect to receive such royalties because of the potential entry of generic versions of Namenda XR. In January 2018, the Company completed a follow-on public offering of 3,450,000 shares of its common stock, which includes the exercise in full by the underwriters of their option to purchase 450,000 shares of common stock, at an offering price of $41.50 per share. Proceeds from the follow-on public offering were approximately $134.1 million , net of underwriting discounts, commissions, and offering-related transaction costs. Inventory Inventory is stated at the lower of cost or estimated net realizable value with cost determined under the first-in first-out method. Inventory consists of raw materials, work-in-process, and GOCOVRI finished goods. Raw materials and work-in-process that may be utilized for both commercial and clinical programs are identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance and are included in inventory. Amounts in inventory associated with clinical development programs are charged to research and development expense when the product enters the research and development process and can no longer be used for commercial purposes and, therefore, does not have “alternative future use”. Costs include active pharmaceutical ingredient (API), third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. If the Company identifies excess, obsolete or unsalable product, the Company will write down its inventory to its net realizable value in the period it is identified. To date, the Company has determined that a reserve for potentially excess, obsolete or unsalable inventory is not required. The Company begins capitalizing costs as inventory when the product candidate receives regulatory approval. Prior to regulatory approval, inventory costs related to product candidates are recorded as research and development expense. The Company received FDA approval for GOCOVRI on August 24, 2017, and began capitalizing inventory manufactured at the FDA approved location, after FDA approval. Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with original maturities, when purchased, of less than three months. Investments The Company classifies its investments as “available-for-sale.” In general, these investments are free of trading restrictions. The Company carries these investments at fair value, based on quoted market prices or other readily available market information. Quoted market prices for U.S. government and corporate bonds include both principal and accrued interest components. Unrealized gains and losses are included in accumulated other comprehensive income, which is reflected as a separate component of stockholders’ equity in its Consolidated Balance Sheets. Gains and losses are recognized when realized in its Consolidated Statements of Income. When the Company determines that an other-than-temporary decline in fair value has occurred, the amount of the decline that is related to a credit loss is recognized in income. Gains and losses are determined using the specific identification method. The Company considers all marketable debt securities with a maturity of less than one year to be short-term investments, with all others considered to be long-term investments. All of the Company’s available-for-sale securities are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is judged to be other-than-temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the investments’ fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, extent of the loss related to credit of the issuer, the expected cash flows from the security, its intent to sell or hold the security, and whether or not the Company will be required to sell the security before the recovery of its amortized cost. Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. Intercompany balances and transactions have been eliminated in consolidation. Segments In accordance with ASC 280-10-50, Segment Reporting, operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company operates in one reportable segment: the development and commercialization of therapeutics targeting chronic disorders of the central nervous system. All revenues for the years ended December 31, 2017 , 2016 , and 2015 were generated in the United States. Revenue Recognition The Company recognizes revenue when all four of the following criteria have been met: (i) persuasive evidence of an arrangement exists, (ii) delivery has occurred or services have been rendered, (iii) the fee is fixed or determinable, and (iv) collectability is reasonably assured. Revenue under license arrangements is recognized based on the performance requirements of the contract. Determinations of whether persuasive evidence of an arrangement exists and whether delivery has occurred or services have been rendered are based on management’s judgments regarding the fixed nature of the fees charged for deliverables and the collectability of those fees. Should changes in conditions cause management to determine that these criteria are not met for any new or modified transactions, revenue recognized could be adversely affected. Product sales, net The Company’s product sales, net, consist of U.S. sales of GOCOVRI and is recognized once all four revenue recognition criteria described above have been met. GOCOVRI was approved by the FDA on August 24, 2017 and the Company commenced shipments of GOCOVRI to a specialty pharmacy (SP) during October 2017. The SP dispenses product to a patient based on the fulfillment of a prescription. The Company’s agreement with its SP provides for transfer of title to the product at the time the product is delivered to the SP. In addition, except for limited circumstances, the SP has no right of product return to the Company. The Company has determined it can reasonably estimate its allowances for rebates and returns at the time title and risk of loss transfers to the SP. Therefore, the Company records revenue when the product is delivered to the SP, which is an approach frequently referred to as the “sell-in” revenue recognition model. The Company recognizes revenue from product sales net of the following allowances at the time of revenue recognition: Distribution fees : Distribution fees include fees paid to the SP for data and prompt payment discounts. Distribution fees are recorded as an offset to revenue based on contractual terms. Rebates : Rebates include mandated discounts under the Medicaid Drug Rebate Program, Medicare Part D Prescription Drug Benefit Program, and TRICARE Retail Pharmacy Refunds Program (TRICARE). Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and are based upon contractual agreements or statutory requirements with benefit providers. The allowance for rebates is estimated based on statutory discount rates and expected utilization at the time of sale. The Company estimates for expected utilization of rebates based on data received from the SP. The allowance for rebates is adjusted quarterly to reflect actual experience. Product Returns : Consistent with industry practice, the Company offers limited product return rights. The Company generally allows for the return of product that is damaged or defective, and within a few months prior to and up to a few months after the product expiration date. The Company does not allow product returns for product that has been dispensed to a patient. The Company considers several factors in the estimation of potential product returns, including, expiration dates of the product shipped, the limited product return rights, third-party data in monitoring channel inventory levels, shelf life of the product, prescription trends, and other relevant factors. Medicare Part D coverage gap : Medicare Part D coverage gap is a federal program to subsidize the costs of prescription drugs for Medicare beneficiaries in the United States, which mandates manufacturers to fund a portion of the Medicare Part D insurance coverage gap for prescription drugs sold to eligible patients. Funding of the coverage gap is generally invoiced and paid in arrears. Medicare Part D coverage gap is accrued at the time of sale based on an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters and is adjusted quarterly based on actual experience. Co-payment assistance : The Company provides co-payment assistance to patients who have commercial insurance and meet certain eligibility requirements. Co-payment assistance is accrued based on actual program participation and estimates of program redemption using data provided by third-party administrators. Each of the above adjustments are recorded at the time of revenue recognition, resulting in a reduction in product sales, net, and an increase in accrued expenses or a reduction in accounts receivable, net. The above adjustments require significant estimates, judgment and information obtained from external sources. If management's estimates differ from actuals, the Company will record adjustments that would affect product sales, net in the period of adjustment. License agreement revenue The Company generates revenue from collaboration and license agreements for the development and commercialization of products. Collaboration and license agreements may include non-refundable upfront license fees, partial or complete reimbursement of research and development costs, contingent consideration payments based on the achievement of defined objectives, and royalties on sales of commercialized products. The Company’s performance obligations under the collaboration and license agreements may include the license or transfer of intellectual property rights, obligations to provide research and development services and related materials, and obligations to participate on certain development and/or commercialization committees with the partners. For revenue agreements with multiple-element arrangements, the Company allocates revenue to each non-contingent element based on the relative-selling-price of each element in an arrangement. When applying the relative-selling-price method, the Company determines the selling price for each deliverable using the following estimation hierarchy: (i) vendor-specific objective evidence of fair value of the deliverable, if it exists, (ii) third-party evidence of selling price, if vendor-specific objective evidence is not available, or (iii) the vendor’s best estimate of selling price, if neither vendor-specific nor third-party evidence is available. Revenue allocated is then recognized when the four basic revenue recognition criteria, mentioned above, are met for each element. The Company recognizes payments that are contingent upon achievement of a substantive milestone in their entirety in the period in which the milestone is achieved. Milestones are defined as events that can only be achieved based on the Company’s performance and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones subject to this guidance. Further, the amounts received must relate solely to prior performance, be reasonable relative to all of the deliverables and payment terms within the agreement and commensurate with the Company’s performance to achieve the milestone after commencement of the agreement. Amounts related to research and development funding and full-time equivalent employees assigned to the license agreement are recognized as the related services or activities are performed, in accordance with the contract terms. Cost of Product Sales Cost of product sales consists primarily of direct and indirect costs related to the manufacturing of GOCOVRI products sold, including third-party manufacturing costs, packaging services, freight, and allocation of overhead costs. Cost of product sales may also include period costs related to certain inventory manufacturing services, inventory adjustment charges, as well as manufacturing variances. In connection with the FDA approval of GOCOVRI on August 24, 2017, the Company began capitalizing inventory manufactured at the FDA approved location starting in August 2017. Prior to receiving regulatory approval for GOCOVRI from the FDA, the Company expensed all costs incurred in the manufacture of GOCOVRI as research and development. Concentration of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents and short and long-term investments. Cash, cash equivalents, and investments are deposited with financial institutions or invested in security issuers that management believes are credit worthy. Deposits may, at times, exceed the amount of insurance provided on such deposits. To date, the Company has not experienced any losses on invested cash and cash equivalents. Risk and Uncertainties The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, rapid technological change, uncertainty of results of clinical trials and reaching milestones, uncertainty of market acceptance of the Company’s products, competition from substitute products and larger companies, protection of proprietary technology, strategic relationships, and dependence on key individuals. Products developed by the Company require approvals from the U.S. Food and Drug Administration (“FDA”) or other international regulatory agencies prior to commercial sales. There can be no assurance that the products will receive the necessary approvals. If the Company is denied approval, approval is delayed, or the Company is unable to maintain approval, it could have a materially adverse impact on the Company. The Company has expended and will continue to expend substantial funds to conduct research, development, and clinical testing of its product candidates. The Company also will be required to expend additional funds to establish commercial-scale manufacturing arrangements and to provide for the marketing and distribution of products that receive regulatory approval. The Company may require additional funds to conduct research and development activities and commercialize its products. Additional funds may not be available on acceptable terms, if at all. If adequate funds are unavailable on a timely basis from operations or additional sources of financing, the Company may have to delay, reduce the scope of or eliminate one or more of its research or development programs or alter its product commercialization plans, which may materially and adversely affect its business, financial condition, and operations. Accounts Receivable, net The Company’s accounts receivable balance consists of amounts due from sales of GOCOVRI and amounts due from Allergan, in accordance with the contract terms of the license agreement. Receivables from sales of GOCOVRI are recorded net of allowances which generally include chargebacks, distribution fees, doubtful accounts, and discounts. Allergan receivables are for research and development funding and full-time equivalent employees assigned to the Allergan license agreement, as well as for reimbursement of external costs, recorded as contra-expense, associated with supporting prosecution and litigation of intellectual property rights. The Company’s estimate of the allowance for doubtful accounts is based on an evaluation of the aging of its receivables. Accounts receivable balances are written off against the allowance when it is probable that the receivable will not be collected. To date, the Company has determined that an allowance for doubtful accounts is not required. Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the term of the lease. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet and any resulting gain or loss is reflected in operations in the period realized. Estimated useful lives by major asset category are as follows: Useful Lives Computer equipment and software 3 years Equipment 5 years Furniture and fixtures 10 years Leases At the inception of a lease, the Company evaluates the lease agreement to determine whether the lease is an operating, capital or build-to-suit lease using the criteria in ASC 840, “Leases.” Certain lease agreements also require the Company to make additional payments for taxes, insurance, and other operating expenses incurred during the lease period, which are expensed as incurred. For operating leases, the Company recognizes rent expense on a straight-line basis over the lease term and records the difference between cash rent payments and the recognition of rent expense as a deferred liability. Where lease agreements contain rent escalation clauses, rent abatements and/or concessions, such as rent holidays and tenant improvement allowances, the Company applies them in the determination of straight-line expense over the lease term. Accounting for Long-Lived Assets The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by the comparison of the carrying amount to the future net cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. There have been no such impairments of long-lived assets as of December 31, 2017 . Clinical Trial Accruals The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites, as well as estimates for the services received and efforts expended pursuant to contracts with multiple research institutions and contract research organizations (“CROs”) that conduct and manage clinical trials on the Company’s behalf. The Company estimates clinical trial expenses based on the services performed pursuant to contracts with research institutions and CROs that conduct and manage clinical trials on its behalf. In accruing service fees, the Company obtains the reported level of patient enrollment at each site and estimates the time period over which services are to be performed and activity expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. Research and Development Research and development (“R&D”) expenses include salaries and related compensation, contractor and consultant fees, external clinical trial expenses performed by CROs, licensing fees, acquired intellectual property with no alternative future use, and facility and administrative expense allocations. In addition, the Company funds R&D at research institutions under agreements that are generally cancelable at its option. Research costs typically consist of applied research and preclinical and toxicology work. Pharmaceutical manufacturing development costs consist of pre-approval inventory purchases, product formulation, chemical analysis, and the transfer and scale-up of manufacturing at facilities operated by the Company’s contract manufacturers. Clinical development costs include the costs of Phase 1, Phase 2, and Phase 3 clinical trials. These costs are a significant component of the Company’s research and development expenses. The Company accrues costs for clinical trial activities performed by CROs and other third parties based upon the estimated amount of work completed on each study as provided by the CRO. These estimates are reviewed for reasonableness by the Company’s internal clinical personnel, and the Company aims to match the accrual to actual services performed by the organizations as determined by patient enrollment levels and related activities. The Company monitors patient enrollment levels and related activities using available information; however, if the Company underestimates activity levels associated with various studies at a given point in time, the Company could be required to record significant additional R&D expenses in future periods when the actual activity level becomes known. The Company charges all such costs to R&D expenses. Non-refundable advance payments are capitalized and expensed as the related goods are delivered or services are performed. Long-Term Debt Long-term debt consists of the Company’s loan agreement with HealthCare Royalty Partners (“HCRP”). The Company accounted for the loan agreement as a debt financing arrangement. Interest expense is accrued using the effective interest rate method over the estimated period the debt will be repaid. Debt issuance costs have been recorded as a debt discount in the Company’s consolidated balance sheets and are being amortized and recorded as interest expense throughout the life of the loan using the effective interest rate method. The Company must make certain assumptions and estimates, including future royalties and net product sales, in determining the expected repayment term and amortization period of the debt discount, as well as the classification between current and long-term portions. The Company periodically assesses these assumptions and estimates, and adjusts the liabilities accordingly. See Note 9 for further details of the Company’s long-term debt. Embedded Derivatives Related to Debt Instruments Embedded derivatives that are required to be bifurcated from their host contract are evaluated and valued separately from the debt instrument. Under the Company’s loan agreement with HCRP, upon the occurrence of a default or a change in control, the Company may be required to make mandatory prepayments of the borrowings. The prepayment premium is considered an embedded derivative, as the holder of the loans may exercise the option to require prepayment by the Company. Further, in the event of a regulatory change that results in a material adverse effect on HCRP’s rate of return, the Company shall pay directly to HCRP an amount that compensates HCRP for such reduction. The embedded derivative is presented as a component of other non-current liabilities. The Company will remeasure the embedded derivatives each reporting period and report changes in the estimated fair value as gains or losses in interest and other income, net, in the condensed consolidated statement of operations. Fair Value of Financial Instruments The carrying value of the Company’s cash and cash equivalents, short-term investments, accounts receivable, long-term investments and other current assets, other assets, accounts payable, accrued liabilities approximate fair value due to the short-term nature or determinable value of these items. See also Note 4 for further details of the Company’s fair value instruments. Income Taxes The Company accounts for income taxes under the asset and liability approach. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company follows the provisions of ASC 740, Income Taxes, under which it assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available. Basic and Diluted Net Loss Per Share Basic net loss per share is based upon the weighted average number of common shares outstanding during the period. Diluted net loss per share is based upon the weighted average number of common shares outstanding and dilutive common stock equivalents outstanding during the period. Common stock equivalents are options granted under the Company’s stock awards plans and are calculated under the treasury stock method. Common equivalent shares from unexercised stock options and unvested restricted stock units are excluded from the computation when there is a loss as their effect is anti-dilutive, or if the exercise price of such options is greater than the average market price of the stock for the period. Stock-Based Compensation The Company accounts for stock-based compensation of stock options granted to employees and directors and for employee stock purchase plan shares by estimating the fair value of stock-based awards using the Black-Scholes option-pricing model. The Company accounts for stock-based compensation of restricted stock units granted to employees based on the closing price of the Company’s common stock on the date of grant. The fair value of stock-based awards, net of estimated forfeitures, is recognized and amortized over the applicable vesting period. All stock options awarded to non-employees are accounted for at the fair value of the consideration received or the fair value of the equity instrument issued, as calculated using the Black-Scholes model. Stock options granted to non-employees are subject to periodic revaluation at each reporting date as the underlying equity instruments vest. In order to estimate the value of share-based awards, the Company uses the Black-Scholes model, which requires the use of certain subjective assumptions. The most significant subjective assumptions are management’s estimates of the expected volatility and the expected term of the award. In addition, judgment is also required in estimating the amount of share-based awards that are expected to be forfeited. If actual results differ significantly from any of these estimates, stock-based compensation expense and the Company’s results of operations could be materially impacted. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers . The amendment in this ASU provides guidance on the revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The core principle of this update provides guidance to identify the performance obligations under the contract(s) with a customer and how to allocate the transaction price to the performance obligations in the contract. It further provides guidance to recognize revenue when (or as) the entity satisfies a performance obligation. This standard will replace most existing revenue recognition guidance. On July 9, 2015, the FASB approved a one-year deferral of the effective date of this standard to 2018 for public companies, with an option that would permit companies to adopt the standard as early as the original effective date of 2017. Early adoption prior to the original effective date is not permitted. Since the issuance of ASU 2014-09, the FASB has issued several amendments which clarify certain points, including ASU 2016-08, Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ; ASU 2016-10, Identifying Performance Obligations and Licensing ; ASU 2016-11, Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ; ASU 2016-12, Narrow-Scope Improvements and Practical Expedients ; ASU 2016-20 , Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers ; and ASU 2017-14, Income Statement-Reporting Comprehensive Income (Topic 220), Re |
