Adamas Pharmaceuticals (ADMS) 10-K 4 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 29, 2018
Document and Entity Information
Entity Registrant Name	Adamas Pharmaceuticals Inc
Entity Central Index Key	1,328,143
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Public Float			$ 568,049,925
Entity Common Stock, Shares Outstanding (in shares)		27,448,990
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Shell Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 56,605	$ 91,316
Available-for-sale securities	154,265	82,126
Accounts receivable, net	5,511	367
Inventory	5,121	1,704
Prepaid expenses and other current assets	6,871	3,662
Total current assets	228,373	179,175
Property and equipment, net	3,652	3,132
Available-for-sale securities, non-current	0	2,991
Prepaid expenses and other non-current assets	2,789	878
Total assets	234,814	186,176
Current liabilities
Accounts payable	6,570	3,878
Accrued liabilities	17,194	12,385
Other current liabilities	512	344
Total current liabilities	24,276	16,607
Long-term debt	117,457	102,647
Other non-current liabilities	3,196	796
Total liabilities	144,929	120,050
Commitments and Contingencies (Note 8)
Stockholders’ equity
Preferred stock, $0.001 par value — 5,000,000 shares authorized, and zero shares issued and outstanding at December 31, 2018 and December 31, 2017	0	0
Common stock, $0.001 par value — 100,000,000 shares authorized, 27,434,358 and 23,320,551 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	32	28
Additional paid-in capital	432,815	277,964
Accumulated other comprehensive loss	(264)	(167)
Accumulated deficit	(342,698)	(211,699)
Total stockholders’ equity	89,885	66,126
Total liabilities and stockholders’ equity	$ 234,814	$ 186,176

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	27,434,358	23,320,551
Common stock, shares outstanding (in shares)	27,434,358	23,320,551

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total revenues	$ 34,046	$ 571	$ 572
Costs and operating expenses:
Cost of product sales	633	17	0
Research and development	39,300	27,168	31,230
Selling, general and administrative, net	109,135	61,312	30,326
Total costs and operating expenses	149,068	88,497	61,556
Loss from operations	(115,022)	(87,926)	(60,984)
Interest and other income, net	3,115	1,351	811
Interest expense	(19,092)	(4,645)	0
Loss before income taxes	(130,999)	(91,220)	(60,173)
Benefit for income taxes	0	(1,730)	(115)
Net loss	$ (130,999)	$ (89,490)	$ (60,058)
Net loss per share, basic and diluted (in dollars per share)	$ (4.87)	$ (3.97)	$ (2.77)
Weighted average shares used in computing net loss per share, basic and diluted (in shares)	26,886	22,558	21,711
Product sales
Revenues:
Total revenues	$ 34,046	$ 568	$ 0
License and grant revenue
Revenues:
Total revenues	$ 0	$ 3	$ 572

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (130,999)	$ (89,490)	$ (60,058)
Unrealized gain (loss) on available-for-sale securities	(97)	26	(35)
Comprehensive loss	$ (131,096)	$ (89,464)	$ (60,093)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2015		18,505,462
Beginning balance at Dec. 31, 2015	$ 116,187	$ 23	$ 178,473	$ (158)	$ (62,151)
Increase (decrease) in shareholders' equity
Exercise of stock options (in shares)		586,956
Exercise of stock options	3,042	$ 1	3,041
Vesting of common stock	34		34
Issuance of common stock in conjunction with Secondary Offering, net of commissions and issuance costs (in shares)		2,875,000
Issuance of common stock in conjunction with Secondary Offering, net of commissions and issuance costs	61,822	$ 3	61,819
Net unrealized gain (loss) on available-for-sale securities	(35)			(35)
Stock issued under employee stock purchase plan (in shares)		46,226
Stock issued under employee stock purchase plan	620		620
Stock-based compensation	10,571		10,571
Net loss	(60,058)				(60,058)
Ending balance (in shares) at Dec. 31, 2016		22,013,644
Ending balance at Dec. 31, 2016	132,183	$ 27	254,558	(193)	(122,209)
Increase (decrease) in shareholders' equity
Exercise of stock options (in shares)		1,183,353
Exercise of stock options	$ 9,034	$ 1	9,033
Restricted stock units vested (in shares)	64,471
Restricted stock units vested	$ 201
Net unrealized gain (loss) on available-for-sale securities	26			26
Stock issued under employee stock purchase plan (in shares)		59,083
Stock issued under employee stock purchase plan	766		766
Stock-based compensation	13,406		13,406
Net loss	(89,490)				(89,490)
Ending balance (in shares) at Dec. 31, 2017		23,320,551
Ending balance at Dec. 31, 2017	66,126	$ 28	277,964	(167)	(211,699)
Increase (decrease) in shareholders' equity
Exercise of stock options (in shares)		478,454
Exercise of stock options	$ 3,362	$ 0	3,362
Restricted stock units vested (in shares)	105,396
Restricted stock units vested	$ 0
Issuance of common stock in conjunction with Secondary Offering, net of commissions and issuance costs (in shares)		3,450,000
Issuance of common stock in conjunction with Secondary Offering, net of commissions and issuance costs	134,268	$ 4	134,264
Net unrealized gain (loss) on available-for-sale securities	(97)			(97)
Stock issued under employee stock purchase plan (in shares)		79,957
Stock issued under employee stock purchase plan	1,237		1,237
Stock-based compensation	15,988		15,988
Net loss	(130,999)				(130,999)
Ending balance (in shares) at Dec. 31, 2018		27,434,358
Ending balance at Dec. 31, 2018	$ 89,885	$ 32	$ 432,815	$ (264)	$ (342,698)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net loss	$ (130,999,000)	$ (89,490,000)	$ (60,058,000)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	1,460,000	1,194,000	808,000
Stock-based compensation	15,786,000	13,367,000	10,571,000
Accretion of interest expense	19,092,000	4,645,000	0
Change in fair value of embedded derivative liability	882,000	(294,000)	0
Net accretion of discounts and amortization of premiums of available-for-sale securities	(1,045,000)	456,000	(301,000)
Loss on disposal of fixed assets	123,000	0	0
Provision for write-down of inventory	232,000	0	0
Changes in assets and liabilities
Accrued interest of available-for-sale securities	74,000	(161,000)	(2,000)
Inventory	(3,273,000)	(1,646,000)	0
Prepaid expenses and other assets	(5,036,000)	(2,036,000)	2,643,000
Accounts receivable, net	(5,144,000)	427,000	490,000
Accounts payable	2,759,000	333,000	502,000
Accrued liabilities and other liabilities	866,000	6,378,000	(2,721,000)
Net cash used in operating activities	(104,223,000)	(66,827,000)	(48,068,000)
Cash flows from investing activities
Purchases of property and equipment	(1,064,000)	(1,258,000)	(1,624,000)
Purchases of available-for-sale securities	(200,354,000)	(62,510,000)	(103,528,000)
Maturities of available-for-sale securities	132,080,000	89,333,000	78,443,000
Net cash provided by (used in) investing activities	(69,338,000)	25,565,000	(26,709,000)
Cash flows from financing activities
Proceeds from public offerings, net of offering costs	134,268,000	0	61,822,000
Proceeds from issuance of long-term debt	0	99,600,000	0
Payment of debt issuance costs	0	(633,000)	0
Proceeds from issuance of common stock upon exercise of stock options	3,345,000	9,110,000	2,966,000
Proceeds from employee stock purchase plan	1,237,000	766,000	620,000
Net cash provided by financing activities	138,850,000	108,843,000	65,408,000
Net increase (decrease) in cash and cash equivalents	(34,711,000)	67,581,000	(9,369,000)
Cash and cash equivalents at beginning of period	91,316,000	23,735,000	33,104,000
Cash and cash equivalents at end of period	56,605,000	91,316,000	23,735,000
Supplemental disclosure
Cash paid for interest	2,618,000	0	0
Supplemental disclosure of noncash activities
Property and equipment in accounts payable and accrued expense	7,000	61,000	148,000
Stock-based compensation capitalized in inventory	202,000	39,000	0
Stock option exercise settled after period end	17,000	0	76,000
Property and equipment acquired through tenant improvement allowance	$ 1,129,000	$ 0	$ 0

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	DESCRIPTION OF BUSINESS Adamas Pharmaceuticals, Inc. (the “Company”) focuses on pioneering time-dependent medicines to meaningfully enhance the daily living experience of those affected by CNS disorders. In August 2017, the U.S. Food and Drug Administration (FDA) approved GOCOVRI™ (amantadine) extended release capsules (previously ADS-5102), the first and only FDA-approved medication indicated for the treatment of dyskinesia in patients with Parkinson’s disease receiving levodopa-based therapy, with or without concomitant dopaminergic medications. The Company is also advancing its pipeline of differentiated investigational programs, which includes: ADS-5102 in development for the treatment of walking impairment in patients with multiple sclerosis; and ADS-4101 (lacosamide) modified release capsules in development for the treatment of partial onset seizures in patients with epilepsy. The Company’s goal is to lessen the burden of chronic CNS disorders on patients, caregivers and society. The Company was incorporated in the State of Delaware on November 15, 2000, and operates as one segment. The Company’s headquarters and operations are located in Emeryville, California.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and 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 and variable consideration, clinical trial accruals, fair value of assets and liabilities including short-term and long-term classification, embedded derivatives, income taxes, inventory, 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. 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. During 2018, the Company recorded a $0.2 million write-down of GOCOVRI inventory. No such charges were recorded in 2017. 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, 2018 , 2017 , and 2016 were generated in the United States. Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers , using the full retrospective transition method. The Company recognizes revenue upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company expenses incremental costs of obtaining a contract as and when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) 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, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. Product sales The Company’s product sales consist of U.S. sales of GOCOVRI. GOCOVRI was approved by the FDA on August 24, 2017, and the Company commenced shipments of GOCOVRI to a specialty pharmacy during October 2017. The Company sells its products principally to a specialty pharmacy and certain specialty distributors (each a “Customer” or collectively its “Customers”). These agreements with its Customers provide for transfer of title to the product at the time the product has been delivered to and accepted by the Customer. The Customer subsequently dispenses product directly to a patient. In addition, except for limited circumstances, the Customer has no right of product return to the Company. The Company recognizes revenue on product sales when the Customer obtains control of the Company’s product, which occurs at a point in time, typically upon delivery to the Customer. The Company has determined that the delivery of its product to Customers constitutes a single performance obligation as there are no other promises to deliver goods or services. Shipping and handling activities are considered to be fulfillment activities and are not considered to be a separate performance obligation. The Company has assessed the existence of a significant financing component in the agreements with its Customers. The trade payment terms with its Customers do not exceed one year and therefore the Company has elected to apply the practical expedient and no amount of consideration has been allocated as a financing component. The Company considers the effects of items which can decrease the transaction price such as variable consideration and consideration payable to a Customer or payer. Amounts related to such items are estimated at contract inception and updated at the end of each reporting period as additional information becomes available. The amount of variable consideration may be constrained and is included in the transaction price only to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Revenue from product sales is recorded after considering the impact of the following variable consideration amounts at the time of revenue recognition: Distribution Fees : Distribution fees include fees paid to the Company’s Customers for data and prompt payment discounts. Distribution fees are recorded 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. Rebates are estimated based on statutory discount rates and expected utilization. The expected utilization of rebates is estimated based on data received from the specialty pharmacy and specialty distributor. The Company uses the expected-value method for estimating rebates and estimates are adjusted quarterly to reflect actual experience. Product Returns : Consistent with industry practice, the Company offers limited product return rights and 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. Product returns have been insignificant to date and are expected to be immaterial in the future. 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. The impact of the Medicare Part D coverage gap is estimated using the expected-value method based on an 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 estimated using the expected-value method based on historical program participation and estimates of program redemption using data provided by third-party administrators. Each of the above items are variable consideration, are recorded at the time of revenue recognition, and require significant estimates, judgment and information obtained from external sources. The Company determined a significant reversal of revenue would not occur in a future period for the estimates of variable consideration detailed above and, therefore, the transaction price was not reduced during the periods presented. If management’s estimates differ from actual results, the Company will record adjustments that would affect product sales 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 milestone payments based on the achievement of defined objectives, and royalties on sales of commercialized products. Such agreements may contain various promises to customers which are generally capable of being distinct and accounted for as separate performance obligations. The Company’s duties and responsibilities under the collaboration and license agreements typically 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. These promises may be regarded as separate performance obligations, or bundled as a single performance obligation, depending upon the nature of the arrangement. For agreements with multiple performance obligations, the Company allocates estimated revenue to each performance obligation at contract inception based on the estimated relative standalone selling price (SSP) of each performance obligation in the arrangement. Revenue allocated to each performance obligation is then recognized when the entity satisfies the performance obligation by transferring control of the promised good or service to the customer. Licenses for Intellectual Property (IP) : If the Company determines that the license for IP is distinct from the other performance obligations identified in the arrangement, revenue from non-refundable, up-front fees allocated to the license is recognized when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, judgment is applied to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments : For contracts with customers that contain payments that are contingent upon achievement of a substantive milestone, at the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative SSP basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment. Reimbursement of Research and Development Costs: Amounts related to research and development funding and full-time equivalent employees assigned to the license agreement are recognized over time as the related services or activities are performed, in accordance with the contract terms. Royalties : For arrangements that include sales-based royalties, and the licensed IP is deemed to be the predominant item to which the royalties relate, the Company recognizes the related royalty revenue at the later of (i) when the related sales occur, or (ii) the satisfaction or partial satisfaction of the performance obligation to which the royalty relates. 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 Risk 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. Risks associated with cash, cash equivalents, and investments are mitigated by the Company’s investment policy which defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. Major Customers The Company has entered into distribution agreements with a specialty pharmacy and certain limited specialty distributors. For the year ended December 31, 2018, the Company’s largest customer represented approximately 99% of the Company’s product revenue, and approximately 99% of the Company’s accounts receivable balance at December 31, 2018. Major Suppliers The Company does not currently have any of its own manufacturing facilities, and therefore it depends on an outsourced manufacturing strategy for the production of GOCOVRI for commercial use and for the production of its product candidates for clinical trials. The Company has contracts in place with one third-party manufacturer that is approved for the commercial production of GOCOVRI and one third-party supplier that is approved for GOCOVRI’s active pharmaceutical ingredient. Although there are potential sources of supply other than the Company’s existing manufacturers and suppliers, any new supplier would be required to qualify under applicable regulatory requirements. 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, 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. Given the nature and historical collectability of the Company’s accounts receivable, the Company determined that an allowance for doubtful accounts was not required at December 31, 2018 . 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 its long-lived assets, including 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, 2018 . Clinical Trial Accruals The Company’s clinical trial accruals are based on estimates of patient enrollment and related activities 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 estimated services performed pursuant to these contracts, as provided by the CRO. These estimates are reviewed for reasonableness by the Company’s internal clinical personnel. 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. 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. 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, amortization period of the debt discount, accretion of interest expense, 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 - Long-Term Debt , 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 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 3 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 equity awards 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. Recent Accounting Pronouncements Accounting Pronouncements Adopted in 2018 In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers with amendments in 2015, 2016, and 2017. 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. In addition, the standard requires disclosure of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. This standard replaces most existing revenue recognition guidance. The Company adopted the new standard effective January 1, 2018, using the full retrospective transition method, and determined the adoption of this guidance to have no material impact on amounts previously reported in its consolidated financial statements. ASU 2014-09 also codified the guidance on other assets and deferred costs relating to contracts with customers with the addition of ASC 340-40. This guidance relates to the accounting for costs of an entity to obtain and fulfill a contract to provide goods or services to the customer. Under the new guidance, an entity shall recognize as

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	BALANCE SHEET COMPONENTS Prepaid expenses and other current assets (in thousands) December 31, 2018 2017 Prepaid expenses $ 2,969 $ 2,638 Prepaid clinical trial 2,299 — Income tax receivable 840 1,007 Other current assets 763 17 Prepaid expenses and other current assets $ 6,871 $ 3,662 Property and equipment, net (in thousands) December 31, 2018 2017 Computer equipment and software $ 3,286 $ 3,289 Equipment 384 252 Furniture and fixtures 336 466 Leasehold improvements 1,891 1,645 5,897 5,652 Less: Accumulated depreciation and amortization (2,245 ) (2,520 ) Property and equipment, net $ 3,652 $ 3,132 Depreciation expense was $1.5 million , $1.2 million , and $0.8 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Accrued liabilities (in thousands) December 31, 2018 2017 Accrued employee related costs $ 7,472 $ 5,499 Clinical trial accruals 2,434 1,720 Accrued consulting and other professional fees 4,230 4,897 Current portion of long-term debt 1,664 — Accrued sales deductions 1,053 91 Other 341 178 Accrued liabilities $ 17,194 $ 12,385

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS In accordance with ASC 820-10, Fair Value Measurements and Disclosures, the Company determines the fair value of financial and non-financial assets and liabilities using the fair value hierarchy, which establishes three levels of inputs that may be used to measure fair value, as follows: • Level 1 inputs, which include quoted prices in active markets for identical assets or liabilities; • Level 2 inputs, which include observable inputs other than Level 1 inputs, such as quoted prices for similar assets or liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability. For available-for-sale securities, the Company reviews trading activity and pricing as of the measurement date. When sufficient quoted pricing for identical securities is not available, the Company uses market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These inputs either represent quoted prices for similar assets in active markets or have been derived from observable market data; and • Level 3 inputs, which include unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the underlying asset or liability. Level 3 assets and liabilities include those whose fair value measurements are determined using pricing models, discounted cash flow methodologies, or similar valuation techniques, as well as significant management judgment or estimation. The following table represents the fair value hierarchy for the Company’s financial assets and liabilities which require fair value measurement on a recurring basis (in thousands): December 31, 2018 Total Level 1 Level 2 Level 3 Assets: Money market $ 17,789 $ 17,789 $ — $ — Corporate debt 19,792 — 19,792 — U.S. Treasury notes 131,512 — 131,512 — Commercial paper $ 2,961 $ — $ 2,961 $ — Total assets measured at fair value $ 172,054 $ 17,789 $ 154,265 $ — Liabilities: Embedded derivative liability $ 1,352 $ — $ — $ 1,352 Total liabilities measured at fair value $ 1,352 $ — $ — $ 1,352 December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Money market $ 68,501 $ 68,501 $ — $ — Corporate debt 23,471 — 23,471 — U.S. Treasury notes 61,646 — 61,646 — Total assets measured at fair value $ 153,618 $ 68,501 $ 85,117 $ — Liabilities: Embedded derivative liability $ 470 $ — $ — $ 470 Total liabilities measured at fair value $ 470 $ — $ — $ 470 Money market funds are highly liquid investments and are actively traded. The pricing information on these investment instruments are readily available and can be independently validated as of the measurement date. This approach results in the classification of these securities as Level 1 of the fair value hierarchy. Corporate debt, U.S. Treasury notes, and commercial paper are measured at fair value using Level 2 inputs. The Company reviews trading activity and pricing for these investments as of each measurement date. When sufficient quoted pricing for identical securities is not available, the Company uses market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These inputs represent quoted prices for similar assets in active markets or these inputs have been derived from observable market data. This approach results in the classification of these securities as Level 2 of the fair value hierarchy. In certain cases where there is limited activity or less transparency around inputs to valuation, the related assets or liabilities are classified as Level 3. The Company classified an embedded derivative related to the Royalty-Backed Loan as a Level 3 liability. The fair value of the embedded derivative as a result of a change in control was calculated using a probability-weighted discounted cash flow model. The model used in valuing this embedded derivative requires the use of significant estimates and assumptions including but not limited to: 1) expected cash flows the Company expects to receive on U.S. net sales of GOCOVRI and on royalties from Allergan on U.S. net sales of Namzaric; 2) the Company’s risk adjusted discount rates; and 3) the probability of a change in control occurring during the term of the note based on the percentage of similar companies that were acquired over the previous five year period. Changes in the estimated fair value of the bifurcated embedded derivative are reported as gains or losses in interest and other income, net, in the consolidated statement of operations. In the periods presented, the Company evaluated the embedded derivative value as a result of an event of default and the value as a result of increased costs due to a regulatory change and considered both to have no material value based on current assessment of probability, but could become material in future periods if a specified event of default or regulatory change became more probable than is currently estimated. See Note 9 “Long-Term Debt” for further description. The following table sets forth a summary of the changes in the estimated fair value of the Company’s embedded derivative, which is measured at fair value as a Level 3 liability on a recurring basis (in thousands): Balance as of December 31, 2016 $ — Issuance of long-term debt with embedded derivative 764 Change in fair value included in interest and other income, net (294 ) Balance as of December 31, 2017 470 Change in fair value included in interest and other income, net 882 Balance as of December 31, 2018 $ 1,352 There were no transfers between any of the levels of the fair value hierarchy during the years ended December 31, 2018 and 2017 .

Investments

Investments	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	INVESTMENTS The Company’s investments consist of corporate debt, U.S. Treasury notes, and commercial paper classified as available-for-sale securities. The Company limits the amount of investment exposure as to institution, maturity, and investment type. To mitigate credit risk, the Company invests in investment grade corporate debt, United States Treasury notes, and commercial paper. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and shown separately as a component of accumulated other comprehensive loss within stockholders’ equity. Realized gains and losses are reclassified from other comprehensive loss to other income on the consolidated statements of operations when incurred. The Company may pay a premium or receive a discount upon the purchase of available-for-sale securities. Interest earned and gains realized on available-for-sale securities and amortization of discounts received and accretion of premiums paid on the purchase of available-for-sale securities are included in investment income. The following table is a summary of amortized cost, unrealized gain and loss, and the fair value of available-for-sale securities as of December 31, 2018 , and 2017 (in thousands): December 31, 2018 Gross Unrealized Gross Unrealized Amortized Cost Gains Losses Fair Value Investments: Corporate debt $ 19,833 $ — $ (41 ) $ 19,792 U.S. Treasury notes 131,735 10 (233 ) 131,512 Commercial paper 2,961 — — 2,961 Total $ 154,529 $ 10 $ (274 ) $ 154,265 Reported as: Short-term investments $ 154,529 $ 10 $ (274 ) $ 154,265 Long-term investments — — — — Total $ 154,529 $ 10 $ (274 ) $ 154,265 December 31, 2017 Gross Unrealized Gross Unrealized Amortized Cost Gains Losses Fair Value Investments: Corporate debt $ 23,507 $ — $ (36 ) $ 23,471 U.S. Treasury notes 61,777 — (131 ) 61,646 Total $ 85,284 $ — $ (167 ) $ 85,117 Reported as: Short-term investments $ 82,280 $ — $ (154 ) $ 82,126 Long-term investments 3,004 — (13 ) 2,991 Total $ 85,284 $ — $ (167 ) $ 85,117 Short-term investments include accrued interest of $ 0.5 million as of December 31, 2018 . Short-term and long-term investments includes accrued interest of $ 0.6 million and $ 14,000 , respectively, as of December 31, 2017 . The Company has not incurred any realized gains or losses on investments for the years ended December 31, 2018 and 2017 . Investments are classified as short-term or long-term depending on the underlying investment’s maturity date. The Company had no investments with a maturity date of greater than 12 months as of December 31, 2018 . All investments with unrealized losses at December 31, 2018 , have been in a loss position for less than twelve months or the loss is not material and were temporary in nature. The Company does not intend to sell the investments that are in an unrealized loss position before recovery of their amortized cost basis.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventory	INVENTORY The Company began capitalizing inventory in August 2017 once the FDA approved GOCOVRI. Inventory consists of the following (in thousands): December 31, 2018 December 31, 2017 Raw materials $ 1,330 $ 859 Work-in-process 2,174 817 Finished goods 1,617 28 Total inventory $ 5,121 $ 1,704

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2018
License Agreements
License Agreements	LICENSE AGREEMENTS In November 2012, the Company granted Forest Laboratories Holdings Limited “Forest”, an indirect wholly-owned subsidiary of Allergan plc (collectively “Allergan”) an exclusive license, with right to sublicense, certain of the Company’s intellectual property rights relating to human therapeutics containing memantine in the United States. In connection with these rights, Allergan markets and sells Namzaric ® and Namenda XR ® for the treatment of moderate to severe dementia related to Alzheimer’s disease. Pursuant to the agreement, Allergan made an upfront payment of $65.0 million which the Company recognized as revenue on a straight-line basis over the period from November 2012 to February 2013. The Company earned and received additional cash payments totaling $ 95.0 million upon achievement by Allergan of certain development and regulatory milestones. In November and December 2013, the Company received a total of $ 40.0 million in milestone payments for the successful completion of studies that supported the New Drug Application (“NDA”) filing with the FDA for Namzaric by Allergan. In May 2014, the Company received an additional $ 25.0 million milestone payment as a result of the FDA’s acceptance of the NDA for Namzaric. In December 2014, the Company received a final $ 30.0 million milestone payment in connection with the FDA approval of Namzaric. These amounts were recorded as revenue when received during 2013 and 2014, respectively. Under the agreement, external costs incurred related to the prosecution and litigation of intellectual property rights are reimbursable. Reimbursable external costs are recorded as a reduction to selling, general and administrative, net. For the twelve months ended December 31, 2018 and 2017 , there were $1,000 and $33,000 of reimbursable external costs, respectively. In addition, the Company may earn tiered royalty payments based on future net sales of Namzaric and Namenda XR; however, Allergan’s obligation to pay royalties for any product covered by the license is eliminated in any quarter where there is significant competition from generics. Beginning in May 2020, the Company will be entitled to receive royalties in the low to mid-teens from Allergan for sales of Namzaric in the United States. Allergan’s obligation to pay royalties with respect to fixed-dose memantine-donepezil products, including Namzaric, continues until the later of (i) 15 years after the commercial launch of the first fixed-dose memantine-donepezil product by Allergan in the United States or (ii) the expiration of the Orange Book listed patents for which Allergan obtained rights from the Company covering such product. Beginning in June 2018, the Company was entitled to receive royalties in the low to mid-single digits for sales of Namenda XR in the United States. The Company does not expect to receive royalties on net sales of Namenda XR, due to the entry of generic versions of Namenda XR. The Company evaluated the Allergan agreement under Topic 606. Based on that evaluation, the Company has determined that at the date of adoption it has satisfied all performance obligations associated with the upfront and milestone payments for each comparative period presented. Royalties under the license agreement will be recognized when the related sales occur, in accordance with the sales-based royalty exception.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Lease Commitments In January 2018, the Company amended its Emeryville, California, operating lease agreement to extend the term of its lease from April 30, 2020, to April 30, 2025, and relocate and expand its office space from 18,500 square feet to 37,626 rentable square feet within the same building. The Company completed its relocation during the third quarter of 2018. The lease provides for a tenant improvement allowance of approximately $1.1 million , which the Company fully utilized during the third quarter of 2018. The tenant improvement allowance is accounted for as a lease incentive obligation and amortized as a reduction of rent expense on a straight-line basis over the term of the lease. The lease provides for periods of escalating rent. The total cash payments over the life of the lease are divided by the total number of months in the lease period and the average rent is charged to expense each month during the lease period. The Company’s total rent expense was approximately $1.2 million , $0.7 million , and $0.6 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Purchase Commitments The Company has entered into agreements for the supply of API and the manufacture of commercial supply of GOCOVRI, with Moehs Ibérica, S.L. and Catalent Pharma Solutions, LLC, respectively. Under the terms of the agreements, the Company will supply the vendors with non-cancelable firm commitment purchase orders and must meet certain annual minimum requirements for the manufacture of commercial supply of GOCOVRI. The Company has also entered into other agreements with certain vendors for the provision of services, including services related to data access and packaging, under which the Company is contractually obligated to make certain payments to the vendors. The Company enters into contracts in the normal course of business that include, among others, arrangements with CROs for clinical trials, vendors for preclinical research, and vendors for manufacturing. These contracts generally provide for termination upon notice, and therefore the Company believes that its obligations under these agreements are not material. As of December 31, 2018 , future minimum lease payments under the non-cancelable facility operating lease, non-cancelable purchase commitments, and annual minimum requirements were as follows (in thousands): December 31, 2018 2019 $ 6,064 2020 3,733 2021 3,406 2022 3,468 2023 2,181 Thereafter 3,011 Total $ 21,863 Contingencies In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown, because it involves claims that may be made against the Company in the future, but have not yet been made. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. Indemnification In accordance with the Company’s amended and restated certificate of incorporation and amended and restated bylaws, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving in such capacity. There have been no claims to date, and the Company has a directors and officers liability insurance policy that may enable it to recover a portion of any amounts paid for future claims. Litigation and Other Legal Proceedings In November 2012, the Company granted Forest an exclusive license to certain of the Company’s intellectual property rights relating to human therapeutics containing memantine in the United States. Under the terms of that license agreement, Forest has the right to enforce such intellectual property rights which are related to its right to market and sell Namzaric and Namenda XR for the treatment of moderate to severe dementia related to Alzheimer’s disease. The Company has a right to participate in, but not control, such enforcement actions by Forest. In 2018 and as of the date of this filing, multiple generic companies have launched generic versions of Namenda XR. As of the date of this filing, a number of companies have submitted ANDAs including one or more certifications pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(iv) to the FDA requesting approval to manufacture and market generic versions of Namzaric, on which the Company is entitled to receive royalties from Forest beginning in May 2020. As of the date of this filing, the Company and Forest have settled with all such Namzaric ANDA filers, including all first filers on all the available dosage forms of Namzaric. Subject to those agreements, the earliest date on which any of these agreements grants a license to market generic version of Namzaric is January 1, 2025 or in the alternative, an option to launch an authorized generic version of Namzaric beginning on January 1, 2026, or earlier in certain circumstances. The Company and Forest intend to continue to enforce the patents associated with Namzaric. On February 16, 2018, Osmotica Pharmaceuticals LLC and Vertical Pharmaceuticals LLC (“Osmotica”) filed an action against the Company in U.S. District Court for the state of Delaware, requesting a declaratory judgment that Osmotica’s newly-approved product Osmolex ER™ (amantadine) extended release tablets does not infringe certain of the Company’s patents. On September 20, 2018, the Company filed its first amended answer including infringement counterclaims against Osmotica asserting Osmotica has infringed nine Company patents under 35 U.S.C. §§ 271(a), (b), and/or (c) and 35 U.S.C. § 271(e)(2)(A) and seeking various forms of relief, including damages, treble damages, injunctive relief, and an order pursuant to 35 U.S.C. § 271(e)(4)(A) that the effective date of any approval of Osmotica’s NDA for Osmolex ER™ be a date that is not earlier than the latest expiration date of the Company patents involved in the lawsuit. This action is ongoing. On March 13, 2018, the FDA’s New Paragraph IV Certifications list was updated to reflect that an ANDA seeking authorization from the FDA to manufacture, use, or sell a generic version of GOCOVRI™ (amantadine) extended release capsules, containing one or more certifications pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (“paragraph IV certification”), was submitted to the FDA on January 16, 2018, and has been accepted for filing. Subsequent to this date, the Company received a letter from attorneys representing Sandoz, Inc. (“Sandoz”) dated March 29, 2018, notifying it that Sandoz filed an ANDA for Amantadine Extended-Release Capsules, 137 mg that contains paragraph IV certifications seeking to obtain approval to engage in the commercial manufacture, use or sale of Amantadine Extended-Release Capsules, 137 mg before the expiration of U.S. Patent Nos. 8,389,578; 8,741,343; 8,796,337; 8,889,740; 8,895,614; 8,895,615; 8,895,616; 8,895,617; 8,895,618; 9,867,791; 9,867,792; 9,867,793; and 9,877,933. On May 10, 2018, the Company filed a lawsuit against Sandoz alleging infringement of the patents against Sandoz in the United States District Court for the District of New Jersey. On July 30, 2018, Sandoz filed its answer, defenses, and counterclaims asserting that the asserted Company patents are invalid and not infringed in response to the Company’s May 10, 2018 complaint. This action is ongoing. From time to time, the Company may be party to legal proceedings, investigations, and claims in the ordinary course of its business. Other than the matters described above, the Company is not currently party to any material legal proceedings.

Long-term Debt

Long-term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt	LONG-TERM DEBT Royalty-Backed Loan Agreement In May 2017, the Company, through a new wholly-owned subsidiary, Adamas Pharma, LLC, entered into a Royalty-Backed Loan with HCRP, whereby the Company initially borrowed $35.0 million , followed by an additional $65.0 million received in the fourth quarter 2017 upon FDA’s recognition in the Orange Book of seven -year orphan drug exclusivity, which GOCOVRI earned upon approval on August 24, 2017. Principal and interest will be payable quarterly from the proceeds of a 12.5% royalty on U.S. net sales of GOCOVRI and up to $15.0 million of the Company’s annual royalties from Allergan on U.S. net sales of Namzaric starting in May 2020, pursuant to the Company’s license agreement with Allergan. The royalty rate on net sales of GOCOVRI will drop to 6.25% after the principal amount of the loan has been repaid in full, until the Company has made total payments of 200% of the funded amounts. The Company may elect to voluntarily prepay the loan at any time, or may be required to prepay subject to specified prepayment trigger events as described below, in which case the amount due will be 200% of the funded amounts, less total payments made to date. Royalty rates are subject to increase to 17.5% and 22.5% if total principal and interest payments have not reached minimum specified levels at measurement dates on December 2021 and December 2022, respectively. Under the terms of the loan, HCRP has recourse to Adamas Pharma, LLC, not the Company. The loan agreement matures in December 2026 but as the repayment of the loan amount is contingent upon the sales volumes of GOCOVRI and royalties from Allergan, the repayment term may be shortened depending on the actual sales of GOCOVRI and actual royalties received from Allergan. The loans bear interest at an annual rate of 11% on the outstanding principal amount and includes an interest-only period until the interest payment date following the ninth full calendar quarter after the $65.0 million additional loan received in the fourth quarter 2017. To the extent that royalties are insufficient to pay interest in full during the first nine quarters of the loan, any unpaid portion of the quarterly interest payment will be added to the principal amount of the loans. In connection with the Royalty-Backed Loan, in 2017 the Company paid HCRP a lender expense amount of $0.4 million and incurred additional debt issuance costs totaling $0.8 million . The lender expense and additional debt issuance costs have been recorded as a debt discount and are being amortized and recorded as interest expense over the estimated term of the loan using the effective interest method. The Company recorded interest expense, including amortization of the debt discount, related to the Royalty-Backed Loan, of $19.1 million and $4.6 million for the twelve months ended December 31, 2018 and 2017 , respectively. Interest expense over the life of the Royalty-Backed Loan includes an annual interest rate of 11% on the outstanding principal, a royalty rate of 6.25% on net sales of GOCOVRI after the principal amount is paid, and amortization of the debt discount. The effective interest rate as of December 31, 2018 on the amounts borrowed under the Royalty-Backed Loan, including the amortization of the debt discount, was 14.5% . The assumptions used in determining the expected repayment term of the loan and amortization period of the debt discount require that the Company make estimates that could impact the short and long-term classification of these costs, as well as the period over which these costs will be amortized and the effective interest rate. The Company may be required to make mandatory prepayments of the borrowings under the Royalty-Backed Loan upon the occurrence of specified prepayment trigger events, including: (1) the occurrence of any event of default or (2) the occurrence of a change in control. Upon the prepayment of all or any of the outstanding principal balance, the Company shall pay, in addition to such prepayment, a prepayment premium. As HCRP, as the holder of the loans, may exercise the option to require prepayment by the Company, the prepayment premium is considered to be an embedded derivative which is required to be bifurcated from its host contract and accounted for as a separate financial instrument. The valuation of the embedded derivative is described further in Note 3 . Payment obligations under the Royalty-Backed Loan are as follows (in thousands): December 31, 2018 December 31, 2017 Total repayment obligation $ 200,000 $ 200,000 Less: Interest to be accreted in future periods (78,261 ) (97,353 ) Less: Payments made (2,618 ) — Carrying value of loans payable $ 119,121 $ 102,647 Less: Current portion of long-term debt (1,664 ) — Non-current portion of long-term debt $ 117,457 $ 102,647 The estimated fair value of the long-term debt, as measured using Level 3 inputs, approximates $95.7 million as of December 31, 2018 . The estimated fair value was calculated in the same methodology as the valuation of the embedded derivative as described further in Note 3 . There are no contractual minimum principal payments due until the loan matures in December 2026 as the repayment of the loan amount is contingent upon the sales volumes of GOCOVRI and royalties from Allergan.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2018
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	CONVERTIBLE PREFERRED STOCK The Company’s amended and restated certificate of incorporation filed on April 15, 2014, authorizes 5,000,000 shares of preferred stock, of which there were no shares outstanding as of December 31, 2018 and 2017 .

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY Common Stock The amended and restated certificate of incorporation authorizes the Company to issue 100,000,000 shares of common stock. Common stockholders are entitled to dividends as and when declared by the board of directors, subject to the rights of holders of all classes of stock outstanding having priority rights as to dividends. There have been no dividends declared to date. Each share of common stock is entitled to one vote. Public Offering In January 2016, the Company completed a follow-on public offering of 2,875,000 shares of common stock, which includes the exercise in full by the underwriters of their option to purchase 375,000 shares of common stock, at an offering price of $23.00 per share. Proceeds from the follow-on public offering were approximately $61.8 million , net of underwriting discounts and offering-related transaction costs. In January 2018, the Company completed a follow-on public offering of 3,450,000 shares of 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 $134.3 million , net of underwriting discounts and offering-related transaction costs. Sales Agreement In May 2017, the Company entered into a sales agreement (“2017 Sales Agreement”) with Cowen and Company, LLC (“Cowen”), as sales agent, pursuant to which the Company may, from time to time, issue and sell at its option, shares of the Company’s common stock for an aggregate offering price of up to $50.0 million under an at-the-market offering (“ATM Offering”). Sales of the common stock, if any, will be made pursuant to a shelf registration statement that was declared effective by the Securities and Exchange Commission (“SEC”) on November 21, 2016. Cowen is acting as sole sales agent for any sales made under the Sales Agreement and the Company will pay Cowen a commission of up to 3% of the gross proceeds. The Company’s common stock will be sold at prevailing market prices at the time of the sale, and, as a result, prices may vary. The Company is not obligated to make any sales of shares of common stock under the Sales Agreement. Unless otherwise terminated earlier, the Sales Agreement continues until all shares available under the Sales Agreement have been sold. As of December 31, 2018 , no shares have been sold under the Sales Agreement. Shares Reserved for Future Issuance Shares of the Company’s common stock reserved for future issuance are as follows: December 31, 2018 December 31, 2017 Common stock awards issued and outstanding 5,949,436 5,564,635 Authorized for future issuance under 2014 Equity Incentive Plan 1,814,179 1,723,733 Authorized for future issuance under 2016 Inducement Plan 512,440 188,715 Employee stock purchase plan 847,105 693,856 Total 9,123,160 8,170,939

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION Stock Compensation Plans In October 2002, the Company established its 2002 Employee, Director, and Consultant Stock Plan and in December 2007, the Company established its 2007 Stock Plan. No further grants were then made under the 2002 Plan. In February 2014, the Company’s board of directors adopted, and in March 2014 the Company’s stockholders approved, the 2014 Equity Incentive Plan (the “2014 Plan”), which became effective on the completion of the IPO. No further grants were then made under the 2007 Plan. Under the 2014 Plan, 1,993,394 shares of the Company’s common stock were made available for issuance which included all shares that, as of the effective time, were reserved for issuance pursuant to the 2007 Plan, and is subject to further increase for shares that were subject to outstanding options under the 2007 Plan and the 2002 Plan as of the effective time that thereafter expire, terminate, or otherwise are forfeited or reacquired. The number of shares of the Company’s common stock reserved for issuance pursuant to the 2014 Plan will automatically increase on the first day of each fiscal year for a period of up to 10 years , commencing on the first day of the fiscal year following 2014, in an amount equal to 4% of the total number of shares of the Company’s capital stock outstanding on the last day of the preceding fiscal year, or a lesser number of shares as determined by the Company’s board of directors. For 2018 , 2017 , 2016 , and 2015 , the common stock available for issuance under the 2014 Plan increased by 932,822 , 880,362 , 739,708 , and 701,763 shares of common stock, respectively. As of December 31, 2018 , the number of shares available for issuance under the 2014 Plan was 1,814,179 . Options granted under the 2014 Stock Plan may have terms of up to ten years. All options issued to date have had a ten year life. The exercise price of an ISO shall not be less than 100% of the estimated fair value of the shares on the date of grant, as determined by the board of directors. The exercise price of an ISO and NSO granted to a 10% stockholder shall not be less than 110% of the estimated fair value of the shares on the date of grant, respectively, as determined by the board of directors. The exercise price of a NSO shall not be less than the par value per share of common stock. The options granted generally vest over four years and vest at a rate of 25% upon the first anniversary of the issuance date and 1/48th per month thereafter. Restricted stock units granted generally vest at a rate of 25% per year over four years. In March 2016, the Company’s board of directors approved the 2016 Inducement Plan (the “Inducement Plan”) under which 450,000 shares of the Company’s common stock were made available for issuance. In each of January 2017 and November 2017, an amendment to the Inducement Plan was approved to increase the number of shares available for issuance an additional 450,000 shares, for a total of 900,000 shares, resulting in a total of 1,350,000 shares of common stock issuable under the Inducement Plan. As of December 31, 2018 , the number of shares available for issuance under the Inducement Plan was 512,440 . Options granted under the Inducement Plan may have terms of up to ten years. All options issued to date have had a ten year life. Consistent with the 2014 Plan, options granted generally vest over four years and vest at a rate of 25% upon the first anniversary of the issuance date and 1/48th per month thereafter. Restricted stock units granted vest at a rate of 25% per year over four years. The Inducement Plan was adopted by the board of directors without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules. Stock Option Activity Stock option activity under all of the Company’s stock compensation plans is summarized as follows: Outstanding Options Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value (thousands) Number of Shares Weighted Average Exercise Price Stock Options Balances, December 31, 2017 5,137,584 $ 12.12 Options granted 1,289,396 25.27 Options exercised (478,454 ) 7.03 Options forfeited (586,197 ) 19.11 Options expired (61,263 ) 14.97 Balances, December 31, 2018 5,301,066 $ 14.98 6.33 $ 6,525 Vested and expected to vest, December 31, 2018 5,179,804 $ 14.81 6.28 $ 6,525 Exercisable, December 31, 2018 3,599,021 $ 11.49 5.18 $ 6,525 The aggregate intrinsic value of options outstanding, vested and expected to vest, and exercisable were calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock as of December 31, 2018 of $8.54 . The intrinsic value of options exercised, calculated as the difference between the exercise price and the fair value of the Company’s common stock on the date of exercise, was approximately $9.2 million , $18.1 million , and $6.6 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. During the years ended December 31, 2018 , 2017 , and 2016 , the Company granted stock options to employees to purchase 1,289,396 , 1,439,675 , and 1,030,375 shares of common stock, respectively, with a weighted-average grant date fair value of $16.08 , $11.93 , and $9.15 , respectively. As of December 31, 2018 , there was total unrecognized compensation cost related to unvested options of approximately $22.1 million . This cost is expected to be recognized over a weighted average remaining vesting period of 2.8 years . The total fair value of employee stock options vested for the years ended December 31, 2018 , 2017 , and 2016 was $12.1 million , $10.6 million and $8.4 million , respectively. Restricted Stock Unit Activity Restricted stock unit activity under all of the Company’s stock compensation plans is summarized as follows: Outstanding Units Weighted-Average Restricted Stock Units Number of Shares Unvested, December 31, 2017 427,051 $ 18.72 Granted 465,372 16.05 Vested (105,396 ) 18.39 Forfeited (138,657 ) 20.07 Unvested, December 31, 2018 648,370 $ 16.57 The aggregate intrinsic value of RSUs outstanding on December 31, 2018 was $5.5 million based on the fair value of the Company’s common stock on that date. The aggregate intrinsic value of RSUs vested for the years ended December 31, 2018 , 2017 , and 2016 was $2.3 million , $1.2 million , and zero , respectively. As of December 31, 2018 , there was total unrecognized compensation cost related to unvested RSUs of approximately $9.4 million . This cost is expected to be recognized over a weighted average remaining vesting period of 2.7 years . Employee Stock Purchase Plan In February 2014, the Company’s board of directors adopted and, in March 2014, the Company’s stockholders approved, the 2014 Employee Stock Purchase Plan (the “ESPP”), which became effective on the completion of the Company’s IPO. The ESPP authorized the issuance of 262,762 shares. Under the ESPP, employees, subject to certain restrictions, may purchase shares of common stock at 85% of the fair market value at either the beginning of the offering period or the date of purchase, whichever is less. Purchases are limited to the lesser of 15% of each employee’s eligible annual compensation or $25,000 . Through the end of 2018 , the Company has issued a total of 229,320 shares under the ESPP. The number of shares available for future issuance under the plan were 847,105 at December 31, 2018 . Beginning January 1, 2015 and continuing through and including January 1, 2024, the amount of common stock reserved for issuance under the ESPP will increase annually on that date by the lesser of (i) one percent ( 1% ) of the total number of shares of common stock outstanding on such December 31, (ii) 520,000 shares of common stock, or (iii) a number of shares as determined by the board of directors prior to the beginning of each year, which shall be the lesser of (i) or (ii) above. For 2018 , 2017 , 2016 , and 2015 , the common stock available for issuance under the ESPP increased by 233,206 , 220,090 , 184,927 , and 175,440 shares of common stock, respectively. Stock-Based Compensation Expense The following table reflects stock-based compensation expense recognized for the years ended December 31, 2018 , 2017 , and 2016 (in thousands): Years Ended December 31, 2018 2017 2016 Research and development $ 2,822 $ 3,597 $ 2,855 Selling, general and administrative 12,964 9,770 7,716 Total stock-based compensation expense $ 15,786 $ 13,367 $ 10,571 Stock-based compensation of $202,000 , $39,000 , and zero was capitalized into inventory for the twelve months ended December 31, 2018 , 2017 , and 2016 . Stock-based compensation capitalized into inventory is recognized as cost of sales when the related product is sold. The Company’s method of valuation for share-based awards is based on the Black-Scholes model. The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to the Company’s expected stock price volatility over the term of the awards, and actual and projected employee stock option exercise behaviors. A description of the assumptions follows: • The expected stock price volatility assumption was determined by examining the historical volatilities of a group of industry peers, as well as taking into consideration the Company’s own historical volatility since its IPO in 2014. • The risk-free interest rate is based on the U.S. Treasury zero-coupon issues with remaining terms similar to the expected term on the options. • The expected term of the options granted represents the average period the stock options are expected to remain outstanding. The Company has elected to use the “simplified method” for estimating the expected term, which is calculated as the mid-point between the vesting period and the contractual term of the options. • The expected dividend yield assumption was based on the fact that the Company has never paid cash dividends and currently has no intention to pay cash dividends. As stock-based compensation expense recognized in the Consolidated Statement of Operations for fiscal years 2018 , 2017 , and 2016 is based on awards ultimately expected to vest, each has been reduced for estimated forfeitures, based on historical experience. The Company estimated the fair value of employee stock options and ESPP shares on the date of grant using the Black-Scholes model with the following weighted-average assumptions: Years Ended December 31, 2018 2017 2016 Stock Options Expected price volatility 67% - 70% 68% - 70% 69% - 71% Risk-free interest rate 2.27% - 3.06% 1.83% - 2.17% 1.23% - 1.81% Expected term (in years) 5.50 - 6.25 5.50 - 6.25 5.50 - 6.25 Dividend yield — — — Years Ended December 31, 2018 2017 2016 Employee Stock Purchase Plan Expected price volatility 62% - 64% 51% - 71% 68% - 73% Risk-free interest rate 2.10% - 2.56% 0.60% - 1.45% 0.49% - 0.60% Expected term (in years) 0.50 0.50 0.50 Dividend yield — — — Stock-based compensation expense related to employee stock options for the years ended December 31, 2018 , 2017 , and 2016 was $12.7 million , $11.2 million , and $9.3 million , respectively. Stock-based compensation expense related to the ESPP plan for the years ended December 31, 2018 , 2017 , and 2016 was $0.6 million , $0.3 million , and $0.3 million , respectively. Stock-based compensation expense related to restricted stock units was $2.3 million , $1.3 million , and $0.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Non-Employee Stock-Based Compensation The Company granted to consultants zero options to purchase common stock and zero restricted stock units during the year ended 2018 ; 5,000 options to purchase common stock and 12,437 restricted stock units during the year ended 2017 ; and 12,600 options to purchase common stock during the year ended 2016 . These restricted stock units and options are granted in exchange for consulting services to be rendered and are measured and recognized as they are earned. Options issued during the year ended 2016 were granted to a member of the Company’s board of directors. The Company believes that the estimated fair value of the restricted stock units and stock options is more readily measurable than the fair value of the services rendered. The Company estimated the fair value of non-employee stock options using the Black-Scholes model with the following weighted-average assumptions: Years Ended December 31, 2018 2017 2016 Expected price volatility 69% - 74% 68% - 80% 71% - 77% Risk-free interest rate 2.32% - 2.45% 1.94% - 2.36% 1.47% - 2.46% Expected term (in years) 6.00 - 9.50 6.00 - 9.75 7.00 - 9.75 Dividend yield — — — Compensation expense related to non-employee restricted stock units and options for years ended December 31, 2018 , 2017 , and 2016 was approximately $0.2 million , $0.6 million , and $0.5 million , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Loss before benefit for income tax is summarized as follows (in thousands): Year Ended December 31, 2018 2017 2016 United States $ (130,999 ) $ (91,220 ) $ (60,147 ) International — — (26 ) Total $ (130,999 ) $ (91,220 ) $ (60,173 ) The benefit for income taxes is summarized as follows (in thousands): December 31, 2018 2017 2016 Current: Federal $ — $ (1,730 ) $ (116 ) State — — 1 Benefit for income taxes $ — $ (1,730 ) $ (115 ) The benefit for income taxes differs from the amount computed by applying the federal income tax rate of 21% to pretax loss from operations as a result of the following: December 31, 2018 2017 2016 Statutory federal income tax rate $ (27,510 ) $ (31,927 ) $ (21,079 ) State income taxes, net of federal tax benefits (10,296 ) (5,041 ) (9 ) Foreign rate differential — — 10 Tax credits (2,587 ) (2,306 ) (3,905 ) Impact of federal rate change — 24,907 — Change in statutory rates 34 (1,440 ) 624 Stock compensation (569 ) (2,558 ) (1,109 ) State net operating losses — 633 1,779 Other 798 — 109 Change in valuation allowance 40,130 16,002 23,465 Income tax benefit $ — $ (1,730 ) $ (115 ) Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): December 31, 2018 2017 Net operating loss carryforwards $ 75,143 $ 44,177 Research and development tax credits 18,776 16,189 Accruals and reserves 4,655 371 Stock compensation 8,662 6,244 Depreciation and amortization 1,437 1,638 Other (rate change) 77 — Total deferred tax assets 108,750 68,619 Less: Valuation allowance (108,750 ) (68,619 ) Net deferred tax assets $ — $ — The deferred income tax assets have been fully offset by a valuation allowance, as realization is dependent on future earnings, if any, the timing and amount of which are uncertain. The net valuation allowance increased by $40.1 million and $16.0 million for the years ended December 31, 2018 and 2017 , respectively. The Company’s accounting for deferred taxes involves the evaluation of a number of factors concerning the realization of its net deferred tax assets. The Company primarily considered such factors as its history of operating losses, the nature of the Company’s deferred tax assets, and the timing, likelihood, and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible. The Tax Act repealed corporate alternative minimum tax (“AMT”) for tax years beginning after December 31, 2017, and provides that existing AMT credit carryovers are refundable beginning in 2018 through 2022. The Company has approximately $1.7 million of AMT credit carryovers that are fully refunded by 2022 and therefore the deferred tax asset has been reclassed to an income tax receivable. As for the remaining deferred tax assets, the Company does not believe that it is more likely than not that the deferred tax assets will be realized; accordingly, a full valuation allowance has been established and no deferred tax asset is shown in the accompanying balance sheets. As of December 31, 2018 , and 2017 , the Company had federal net operating loss carryforwards of approximately $271.6 million and $163.3 million , respectively, available to reduce future taxable income. The Company also had state net operating loss carryforwards of approximately $236.2 million and $131.3 million as of December 31, 2018 and 2017 , respectively. The federal net operating loss carryforward begins expiring in 2025, and state net operating loss carryforward begins expiring in 2028. The Company has federal research and development tax credit carryforwards of approximately $5.2 million . If not utilized, the carryforwards will begin expiring in 2024. The Company has state research and development credit carryforwards of approximately $3.9 million which do not expire. The Company also has orphan drug credit carryforwards of $14.4 million . Under federal and similar state tax statutes, changes in the Company’s ownership may limit its ability to use its available net operating loss and tax credit carryforwards. The annual limitation, as a result of a change of control, may result in the expiration of net operating losses and credits before utilization. The Company’s ability to use its remaining net operating loss and tax credit carryforwards may be further limited if the Company experiences a Section 382 ownership change in connection with future changes in its stock ownership. Uncertain Tax Positions The total amounts of unrecognized tax benefits for the years ended December 31, 2018 , 2017 , and 2016 were $4.7 million , $4.0 million , and $3.2 million , respectively. If recognized, none of the unrecognized tax benefits would affect the effective tax rate. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): December 31, 2018 2017 2016 Balance at the beginning of the year $ 4,034 $ 3,188 $ 1,820 Additions based on prior period tax positions 220 43 93 Additions based on current period tax positions 443 803 1,275 Balance at the end of the year $ 4,697 $ 4,034 $ 3,188 The Company’s policy is to account for interest and penalties as income tax expense. The Company accrued no interest related to unrecognized tax benefits during the years ended December 31, 2018 , 2017 , and 2016 . The Company files income tax returns in the U.S. federal jurisdiction, California, other state jurisdictions, and India. The Company is subject to U.S. federal income tax examination for the calendar years ending 2002 through 2018 due to net operating losses that have been carried forward for tax purposes. Additionally, the Company is subject to state income tax examinations for the 2006 through 2018 calendar years due to net operating losses that are being carried forward for tax purposes. The Company is subject to audit by the Indian tax authorities from 2014 onward. The Company is not currently under audit in any major tax jurisdiction. On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act made broad and complex changes to the U.S. tax code, including, but not limited to, reducing the U.S. federal corporate tax rate from 35 percent to 21 percent for tax years beginning after December 31, 2017. Pursuant to the SEC Staff Accounting Bulletin No. 118, “Income Tax Accounting Implications of the Tax Cuts and Jobs Act” (“SAB 118”), a company may select between one of three scenarios to determine a reasonable estimate arising from the Tax Act. Those scenarios are (i) a final estimate which effectively closes the measurement window; (ii) a reasonable estimate leaving the measurement window open for future revisions; and (iii) no estimate as the law is still being analyzed. The Company was able to provide a reasonable estimate for the revaluation of deferred taxes, primarily driven by corporate rate reduction, by recording a net tax provision of $24.9 million in the period ended December 31, 2017, which was offset by a full valuation allowance. The Company also recorded in 2017 a tax benefit of $1.7 million for AMT credits which are refundable in tax year 2018 through 2022. During the quarter ended December 31, 2018, the Company completed its accounting for the impact of the Tax Act and there were no material changes to amounts previously recorded. Portions of the Tax Act are scheduled to be implemented in future years and therefore the Company will continue to assess its positions and possible implications.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss per Share	NET LOSS PER SHARE The following table presents the calculation of the basic and diluted net loss per share (in thousands, except per share data): December 31, 2018 2017 2016 Net loss attributable to common stockholders, basic and diluted $ (130,999 ) $ (89,490 ) $ (60,058 ) Weighted average common shares used in calculating net loss per common share, basic and diluted 26,886 22,558 21,711 Net loss per share attributable to common stockholders, basic and diluted $ (4.87 ) $ (3.97 ) $ (2.77 ) For all periods presented, there is no difference in the number of shares used to compute basic and diluted shares outstanding due to the Company’s net loss position. The following total outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the periods presented, because including them would have been anti-dilutive (in thousands): December 31, 2018 2017 2016 Options to purchase common stock 5,301 5,138 5,270 Restricted stock units 648 427 213 Total 5,949 5,565 5,483

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	QUARTERLY FINANCIAL INFORMATION (UNAUDITED) The following table represents certain unaudited quarterly information for the eight quarters ended December 31, 2018 . This data has been derived from unaudited consolidated financial statements that, in the opinion of the Company’s management, include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of such information when read in conjunction with the Company’s annual audited consolidated financial statements and notes thereto appearing elsewhere in this report. These operating results are not necessarily indicative of results for any future period (in thousands, except per share data): Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 2,553 $ 7,565 $ 10,613 $ 13,315 Gross profit(2) 2,528 7,492 10,513 12,880 Net loss (34,971 ) (33,993 ) (33,152 ) (28,883 ) Net loss per share, basic and diluted (1.35 ) (1.26 ) (1.22 ) (1.06 ) Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ — $ 2 $ 1 $ 568 (1) Gross profit(2) — — — 551 Net loss (16,028 ) (20,745 ) (23,360 ) (29,357 ) Net loss per share, basic and diluted (0.72 ) (0.93 ) (1.04 ) (1.27 ) (1) In the fourth quarter of 2017 the Company commenced commercial sales of GOCOVRI. (2) Gross profit is computed by subtracting cost of product sales from product sales.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	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	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 and variable consideration, clinical trial accruals, fair value of assets and liabilities including short-term and long-term classification, embedded derivatives, income taxes, inventory, 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.
Inventory	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. During 2018, the Company recorded a $0.2 million write-down of GOCOVRI inventory. No such charges were recorded in 2017. 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 Cash and cash equivalents consist of highly liquid investments with original maturities, when purchased, of less than three months.
Investments	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	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.
Segment	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.
Revenue Recognition and Cost of Product Sales	Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers , using the full retrospective transition method. The Company recognizes revenue upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company expenses incremental costs of obtaining a contract as and when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) 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, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. Product sales The Company’s product sales consist of U.S. sales of GOCOVRI. GOCOVRI was approved by the FDA on August 24, 2017, and the Company commenced shipments of GOCOVRI to a specialty pharmacy during October 2017. The Company sells its products principally to a specialty pharmacy and certain specialty distributors (each a “Customer” or collectively its “Customers”). These agreements with its Customers provide for transfer of title to the product at the time the product has been delivered to and accepted by the Customer. The Customer subsequently dispenses product directly to a patient. In addition, except for limited circumstances, the Customer has no right of product return to the Company. The Company recognizes revenue on product sales when the Customer obtains control of the Company’s product, which occurs at a point in time, typically upon delivery to the Customer. The Company has determined that the delivery of its product to Customers constitutes a single performance obligation as there are no other promises to deliver goods or services. Shipping and handling activities are considered to be fulfillment activities and are not considered to be a separate performance obligation. The Company has assessed the existence of a significant financing component in the agreements with its Customers. The trade payment terms with its Customers do not exceed one year and therefore the Company has elected to apply the practical expedient and no amount of consideration has been allocated as a financing component. The Company considers the effects of items which can decrease the transaction price such as variable consideration and consideration payable to a Customer or payer. Amounts related to such items are estimated at contract inception and updated at the end of each reporting period as additional information becomes available. The amount of variable consideration may be constrained and is included in the transaction price only to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Revenue from product sales is recorded after considering the impact of the following variable consideration amounts at the time of revenue recognition: Distribution Fees : Distribution fees include fees paid to the Company’s Customers for data and prompt payment discounts. Distribution fees are recorded 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. Rebates are estimated based on statutory discount rates and expected utilization. The expected utilization of rebates is estimated based on data received from the specialty pharmacy and specialty distributor. The Company uses the expected-value method for estimating rebates and estimates are adjusted quarterly to reflect actual experience. Product Returns : Consistent with industry practice, the Company offers limited product return rights and 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. Product returns have been insignificant to date and are expected to be immaterial in the future. 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. The impact of the Medicare Part D coverage gap is estimated using the expected-value method based on an 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 estimated using the expected-value method based on historical program participation and estimates of program redemption using data provided by third-party administrators. Each of the above items are variable consideration, are recorded at the time of revenue recognition, and require significant estimates, judgment and information obtained from external sources. The Company determined a significant reversal of revenue would not occur in a future period for the estimates of variable consideration detailed above and, therefore, the transaction price was not reduced during the periods presented. If management’s estimates differ from actual results, the Company will record adjustments that would affect product sales 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 milestone payments based on the achievement of defined objectives, and royalties on sales of commercialized products. Such agreements may contain various promises to customers which are generally capable of being distinct and accounted for as separate performance obligations. The Company’s duties and responsibilities under the collaboration and license agreements typically 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. These promises may be regarded as separate performance obligations, or bundled as a single performance obligation, depending upon the nature of the arrangement. For agreements with multiple performance obligations, the Company allocates estimated revenue to each performance obligation at contract inception based on the estimated relative standalone selling price (SSP) of each performance obligation in the arrangement. Revenue allocated to each performance obligation is then recognized when the entity satisfies the performance obligation by transferring control of the promised good or service to the customer. Licenses for Intellectual Property (IP) : If the Company determines that the license for IP is distinct from the other performance obligations identified in the arrangement, revenue from non-refundable, up-front fees allocated to the license is recognized when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, judgment is applied to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments : For contracts with customers that contain payments that are contingent upon achievement of a substantive milestone, at the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative SSP basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment. Reimbursement of Research and Development Costs: Amounts related to research and development funding and full-time equivalent employees assigned to the license agreement are recognized over time as the related services or activities are performed, in accordance with the contract terms. Royalties : For arrangements that include sales-based royalties, and the licensed IP is deemed to be the predominant item to which the royalties relate, the Company recognizes the related royalty revenue at the later of (i) when the related sales occur, or (ii) the satisfaction or partial satisfaction of the performance obligation to which the royalty relates. 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	Concentration of Risk 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. Risks associated with cash, cash equivalents, and investments are mitigated by the Company’s investment policy which defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. Major Customers The Company has entered into distribution agreements with a specialty pharmacy and certain limited specialty distributors. For the year ended December 31, 2018, the Company’s largest customer represented approximately 99% of the Company’s product revenue, and approximately 99% of the Company’s accounts receivable balance at December 31, 2018. Major Suppliers The Company does not currently have any of its own manufacturing facilities, and therefore it depends on an outsourced manufacturing strategy for the production of GOCOVRI for commercial use and for the production of its product candidates for clinical trials. The Company has contracts in place with one third-party manufacturer that is approved for the commercial production of GOCOVRI and one third-party supplier that is approved for GOCOVRI’s active pharmaceutical ingredient. Although there are potential sources of supply other than the Company’s existing manufacturers and suppliers, any new supplier would be required to qualify under applicable regulatory requirements.
Accounts Receivable, net	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, 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.
Property and Equipment	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	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	Accounting for Long-Lived Assets The Company reviews its long-lived assets, including 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.
Clinical Trial Accruals	Clinical Trial Accruals The Company’s clinical trial accruals are based on estimates of patient enrollment and related activities 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 estimated services performed pursuant to these contracts, as provided by the CRO. These estimates are reviewed for reasonableness by the Company’s internal clinical personnel. 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. 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 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.
Long-Term Debt	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, amortization period of the debt discount, accretion of interest expense, 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 - Long-Term Debt , for further details of the Company’s long-term debt.
Embedded Derivatives Related to Debt Instruments	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 consolidated statement of operations.
Fair Value of Financial Instruments	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 3 for further details of the Company’s fair value instruments.
Income Taxes	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 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 equity awards 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	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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Adopted in 2018 In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers with amendments in 2015, 2016, and 2017. 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. In addition, the standard requires disclosure of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. This standard replaces most existing revenue recognition guidance. The Company adopted the new standard effective January 1, 2018, using the full retrospective transition method, and determined the adoption of this guidance to have no material impact on amounts previously reported in its consolidated financial statements. ASU 2014-09 also codified the guidance on other assets and deferred costs relating to contracts with customers with the addition of ASC 340-40. This guidance relates to the accounting for costs of an entity to obtain and fulfill a contract to provide goods or services to the customer. Under the new guidance, an entity shall recognize as an asset the incremental costs of obtaining a contract with a customer if the entity expects to recover those costs. In the Company’s review of the various costs to obtain contracts with customers, it has determined that currently no significant costs are incurred that meet the capitalization criteria. The Company’s costs to fulfill contracts are outside the scope of ASC 340-40 and are typically expensed as incurred. In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718) – Scope of Modification Accounting. The new guidance clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. The Company adopted the new standard effective January 1, 2018, on a prospective basis. The adoption of this guidance did not have an impact on the Company’s consolidated financial statements or disclosures. New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . The authoritative guidance significantly amends the current accounting for leases. Under the new provisions, all lessees will report a right-of-use asset and a liability for the obligation to make payments for all leases with the exception of those leases with a term of 12 months or less. All other leases will fall into one of two categories: (i) a financing lease or (ii) an operating lease. Lessor accounting remains substantially unchanged with the exception that no leases entered into after the effective date will be classified as leveraged leases. For sale leaseback transactions, a sale will only be recognized if the criteria in the new revenue recognition standard are met. For public business entities, this guidance is effective for fiscal periods beginning after December 15, 2018 and interim periods thereafter. Early adoption is permitted. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842 (Leases) , which amends narrow aspects of the guidance issued in the amendments in ASU 2016-02, and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which allows entities to recognize a cumulative-effect adjustment from the application of ASU 2016-02 to the opening balance of retained earnings in the period of adoption. The Company will adopt the standard in the first quarter of 2019 using this optional method. Pursuant to the guidance, the Company also plans to elect the optional package of practical expedients, which will allow the Company to not reassess: (i) whether any expired or existing contracts are considered or contain leases; (ii) lease classification for any expired or existing leases; and (iii) initial direct costs for any existing leases. The new standard also allows entities to make certain policy elections, including a policy to separate lease and non-lease components, which the Company also plans to elect. The Company is still evaluating the effect the new guidance will have on its consolidated financial statements and disclosures; however, it anticipates that the new standard will result in the Company recording additional right-of-use assets and corresponding lease liabilities on its consolidated balance sheet. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses of Financial Instruments, and in November 2018 the FASB issued a subsequent amendment ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses. The new guidance changes the methodology for measuring credit losses on financial instruments and the timing of when such losses are recorded. This guidance is effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the effect the new guidance will have on its consolidated financial statements. In June 2018, the FASB issued ASU 2018-07, Compensation – Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting , which expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. Previously, accounting for share-based payments to employees was covered by ASC Topic 718 while accounting for such payments to non-employees was covered by ASC Subtopic 505-50. Under this new guidance, both sets of awards, for employees and non-employees, will essentially follow the same model, with small variations related to determining the term assumption when valuing a non-employee award as well as a different expense attribution model for non-employee awards as opposed to employee awards. This guidance is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. The Company is currently evaluating the effect the new guidance will have on its consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement , which modifies the disclosure requirements on fair value measurements. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the effect the new guidance will have on its consolidated financial statements. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which amends ASC 808 to clarify ASC 606 should apply in entirety to certain transactions between collaborative arrangement participants. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the effect the new guidance will have on its consolidated financial statements.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of estimated useful lives by major asset category	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 Property and equipment, net (in thousands) December 31, 2018 2017 Computer equipment and software $ 3,286 $ 3,289 Equipment 384 252 Furniture and fixtures 336 466 Leasehold improvements 1,891 1,645 5,897 5,652 Less: Accumulated depreciation and amortization (2,245 ) (2,520 ) Property and equipment, net $ 3,652 $ 3,132

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule of prepaid expenses and other current assets	Prepaid expenses and other current assets (in thousands) December 31, 2018 2017 Prepaid expenses $ 2,969 $ 2,638 Prepaid clinical trial 2,299 — Income tax receivable 840 1,007 Other current assets 763 17 Prepaid expenses and other current assets $ 6,871 $ 3,662
Schedule of property and equipment, net	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 Property and equipment, net (in thousands) December 31, 2018 2017 Computer equipment and software $ 3,286 $ 3,289 Equipment 384 252 Furniture and fixtures 336 466 Leasehold improvements 1,891 1,645 5,897 5,652 Less: Accumulated depreciation and amortization (2,245 ) (2,520 ) Property and equipment, net $ 3,652 $ 3,132
Schedule of accrued liabilities	Accrued liabilities (in thousands) December 31, 2018 2017 Accrued employee related costs $ 7,472 $ 5,499 Clinical trial accruals 2,434 1,720 Accrued consulting and other professional fees 4,230 4,897 Current portion of long-term debt 1,664 — Accrued sales deductions 1,053 91 Other 341 178 Accrued liabilities $ 17,194 $ 12,385

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of fair value hierarchy for the Company’s financial assets and liabilities which require fair value measurement on a recurring basis	The following table represents the fair value hierarchy for the Company’s financial assets and liabilities which require fair value measurement on a recurring basis (in thousands): December 31, 2018 Total Level 1 Level 2 Level 3 Assets: Money market $ 17,789 $ 17,789 $ — $ — Corporate debt 19,792 — 19,792 — U.S. Treasury notes 131,512 — 131,512 — Commercial paper $ 2,961 $ — $ 2,961 $ — Total assets measured at fair value $ 172,054 $ 17,789 $ 154,265 $ — Liabilities: Embedded derivative liability $ 1,352 $ — $ — $ 1,352 Total liabilities measured at fair value $ 1,352 $ — $ — $ 1,352 December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Money market $ 68,501 $ 68,501 $ — $ — Corporate debt 23,471 — 23,471 — U.S. Treasury notes 61,646 — 61,646 — Total assets measured at fair value $ 153,618 $ 68,501 $ 85,117 $ — Liabilities: Embedded derivative liability $ 470 $ — $ — $ 470 Total liabilities measured at fair value $ 470 $ — $ — $ 470
Schedule of roll forward of the financial instruments classified within Level 3 of the fair value hierarchy	The following table sets forth a summary of the changes in the estimated fair value of the Company’s embedded derivative, which is measured at fair value as a Level 3 liability on a recurring basis (in thousands): Balance as of December 31, 2016 $ — Issuance of long-term debt with embedded derivative 764 Change in fair value included in interest and other income, net (294 ) Balance as of December 31, 2017 470 Change in fair value included in interest and other income, net 882 Balance as of December 31, 2018 $ 1,352

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of amortized cost, unrealized gain and loss and the fair value of available-for-sale securities	The following table is a summary of amortized cost, unrealized gain and loss, and the fair value of available-for-sale securities as of December 31, 2018 , and 2017 (in thousands): December 31, 2018 Gross Unrealized Gross Unrealized Amortized Cost Gains Losses Fair Value Investments: Corporate debt $ 19,833 $ — $ (41 ) $ 19,792 U.S. Treasury notes 131,735 10 (233 ) 131,512 Commercial paper 2,961 — — 2,961 Total $ 154,529 $ 10 $ (274 ) $ 154,265 Reported as: Short-term investments $ 154,529 $ 10 $ (274 ) $ 154,265 Long-term investments — — — — Total $ 154,529 $ 10 $ (274 ) $ 154,265 December 31, 2017 Gross Unrealized Gross Unrealized Amortized Cost Gains Losses Fair Value Investments: Corporate debt $ 23,507 $ — $ (36 ) $ 23,471 U.S. Treasury notes 61,777 — (131 ) 61,646 Total $ 85,284 $ — $ (167 ) $ 85,117 Reported as: Short-term investments $ 82,280 $ — $ (154 ) $ 82,126 Long-term investments 3,004 — (13 ) 2,991 Total $ 85,284 $ — $ (167 ) $ 85,117

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Schedule of inventory	The Company began capitalizing inventory in August 2017 once the FDA approved GOCOVRI. Inventory consists of the following (in thousands): December 31, 2018 December 31, 2017 Raw materials $ 1,330 $ 859 Work-in-process 2,174 817 Finished goods 1,617 28 Total inventory $ 5,121 $ 1,704

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments under the non-cancelable facility operating lease, non-cancelable purchase commitments, and annual minimum requirements	As of December 31, 2018 , future minimum lease payments under the non-cancelable facility operating lease, non-cancelable purchase commitments, and annual minimum requirements were as follows (in thousands): December 31, 2018 2019 $ 6,064 2020 3,733 2021 3,406 2022 3,468 2023 2,181 Thereafter 3,011 Total $ 21,863

Long-term Debt (Tables)

Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of long-term debt and unamortized debt discount balances	Payment obligations under the Royalty-Backed Loan are as follows (in thousands): December 31, 2018 December 31, 2017 Total repayment obligation $ 200,000 $ 200,000 Less: Interest to be accreted in future periods (78,261 ) (97,353 ) Less: Payments made (2,618 ) — Carrying value of loans payable $ 119,121 $ 102,647 Less: Current portion of long-term debt (1,664 ) — Non-current portion of long-term debt $ 117,457 $ 102,647

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of shares of Company's common stock reserved for future issuance	Shares of the Company’s common stock reserved for future issuance are as follows: December 31, 2018 December 31, 2017 Common stock awards issued and outstanding 5,949,436 5,564,635 Authorized for future issuance under 2014 Equity Incentive Plan 1,814,179 1,723,733 Authorized for future issuance under 2016 Inducement Plan 512,440 188,715 Employee stock purchase plan 847,105 693,856 Total 9,123,160 8,170,939

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of activity under the company's stock option plans	Stock option activity under all of the Company’s stock compensation plans is summarized as follows: Outstanding Options Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value (thousands) Number of Shares Weighted Average Exercise Price Stock Options Balances, December 31, 2017 5,137,584 $ 12.12 Options granted 1,289,396 25.27 Options exercised (478,454 ) 7.03 Options forfeited (586,197 ) 19.11 Options expired (61,263 ) 14.97 Balances, December 31, 2018 5,301,066 $ 14.98 6.33 $ 6,525 Vested and expected to vest, December 31, 2018 5,179,804 $ 14.81 6.28 $ 6,525 Exercisable, December 31, 2018 3,599,021 $ 11.49 5.18 $ 6,525
Schedule of restricted stock unit and related activity	Restricted stock unit activity under all of the Company’s stock compensation plans is summarized as follows: Outstanding Units Weighted-Average Restricted Stock Units Number of Shares Unvested, December 31, 2017 427,051 $ 18.72 Granted 465,372 16.05 Vested (105,396 ) 18.39 Forfeited (138,657 ) 20.07 Unvested, December 31, 2018 648,370 $ 16.57
Schedule of allocation of total stock-based compensation expense	The following table reflects stock-based compensation expense recognized for the years ended December 31, 2018 , 2017 , and 2016 (in thousands): Years Ended December 31, 2018 2017 2016 Research and development $ 2,822 $ 3,597 $ 2,855 Selling, general and administrative 12,964 9,770 7,716 Total stock-based compensation expense $ 15,786 $ 13,367 $ 10,571
Schedule of assumptions used to estimate fair value of stock options	The Company estimated the fair value of non-employee stock options using the Black-Scholes model with the following weighted-average assumptions: Years Ended December 31, 2018 2017 2016 Expected price volatility 69% - 74% 68% - 80% 71% - 77% Risk-free interest rate 2.32% - 2.45% 1.94% - 2.36% 1.47% - 2.46% Expected term (in years) 6.00 - 9.50 6.00 - 9.75 7.00 - 9.75 Dividend yield — — — The Company estimated the fair value of employee stock options and ESPP shares on the date of grant using the Black-Scholes model with the following weighted-average assumptions: Years Ended December 31, 2018 2017 2016 Stock Options Expected price volatility 67% - 70% 68% - 70% 69% - 71% Risk-free interest rate 2.27% - 3.06% 1.83% - 2.17% 1.23% - 1.81% Expected term (in years) 5.50 - 6.25 5.50 - 6.25 5.50 - 6.25 Dividend yield — — — Years Ended December 31, 2018 2017 2016 Employee Stock Purchase Plan Expected price volatility 62% - 64% 51% - 71% 68% - 73% Risk-free interest rate 2.10% - 2.56% 0.60% - 1.45% 0.49% - 0.60% Expected term (in years) 0.50 0.50 0.50 Dividend yield — — —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Summary of loss before benefit for income tax	Loss before benefit for income tax is summarized as follows (in thousands): Year Ended December 31, 2018 2017 2016 United States $ (130,999 ) $ (91,220 ) $ (60,147 ) International — — (26 ) Total $ (130,999 ) $ (91,220 ) $ (60,173 )
Summary of income tax benefit	The benefit for income taxes is summarized as follows (in thousands): December 31, 2018 2017 2016 Current: Federal $ — $ (1,730 ) $ (116 ) State — — 1 Benefit for income taxes $ — $ (1,730 ) $ (115 )
Schedule showing the difference of benefit for income taxes from the amount computed by applying the federal income tax rate of 35% to pretax income (loss) from operations	The benefit for income taxes differs from the amount computed by applying the federal income tax rate of 21% to pretax loss from operations as a result of the following: December 31, 2018 2017 2016 Statutory federal income tax rate $ (27,510 ) $ (31,927 ) $ (21,079 ) State income taxes, net of federal tax benefits (10,296 ) (5,041 ) (9 ) Foreign rate differential — — 10 Tax credits (2,587 ) (2,306 ) (3,905 ) Impact of federal rate change — 24,907 — Change in statutory rates 34 (1,440 ) 624 Stock compensation (569 ) (2,558 ) (1,109 ) State net operating losses — 633 1,779 Other 798 — 109 Change in valuation allowance 40,130 16,002 23,465 Income tax benefit $ — $ (1,730 ) $ (115 )
Schedule of deferred tax assets and liabilities	Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands): December 31, 2018 2017 Net operating loss carryforwards $ 75,143 $ 44,177 Research and development tax credits 18,776 16,189 Accruals and reserves 4,655 371 Stock compensation 8,662 6,244 Depreciation and amortization 1,437 1,638 Other (rate change) 77 — Total deferred tax assets 108,750 68,619 Less: Valuation allowance (108,750 ) (68,619 ) Net deferred tax assets $ — $ —
Schedule of reconciliation of the beginning and ending amount of unrecognized tax benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): December 31, 2018 2017 2016 Balance at the beginning of the year $ 4,034 $ 3,188 $ 1,820 Additions based on prior period tax positions 220 43 93 Additions based on current period tax positions 443 803 1,275 Balance at the end of the year $ 4,697 $ 4,034 $ 3,188

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of reconciliation of numerator and denominator used in calculation of basic and diluted net loss per share	The following table presents the calculation of the basic and diluted net loss per share (in thousands, except per share data): December 31, 2018 2017 2016 Net loss attributable to common stockholders, basic and diluted $ (130,999 ) $ (89,490 ) $ (60,058 ) Weighted average common shares used in calculating net loss per common share, basic and diluted 26,886 22,558 21,711 Net loss per share attributable to common stockholders, basic and diluted $ (4.87 ) $ (3.97 ) $ (2.77 )
Schedule of outstanding shares of potentially dilutive securities excluded from the computation of diluted net loss per share of common stock, because including them would have been anti-dilutive	The following total outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the periods presented, because including them would have been anti-dilutive (in thousands): December 31, 2018 2017 2016 Options to purchase common stock 5,301 5,138 5,270 Restricted stock units 648 427 213 Total 5,949 5,565 5,483

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of unaudited quarterly information	These operating results are not necessarily indicative of results for any future period (in thousands, except per share data): Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 2,553 $ 7,565 $ 10,613 $ 13,315 Gross profit(2) 2,528 7,492 10,513 12,880 Net loss (34,971 ) (33,993 ) (33,152 ) (28,883 ) Net loss per share, basic and diluted (1.35 ) (1.26 ) (1.22 ) (1.06 ) Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ — $ 2 $ 1 $ 568 (1) Gross profit(2) — — — 551 Net loss (16,028 ) (20,745 ) (23,360 ) (29,357 ) Net loss per share, basic and diluted (0.72 ) (0.93 ) (1.04 ) (1.27 ) (1) In the fourth quarter of 2017 the Company commenced commercial sales of GOCOVRI. (2) Gross profit is computed by subtracting cost of product sales from product sales.

Description of Business (Detail

Description of Business (Details)	12 Months Ended
	Dec. 31, 2018segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Inventory (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Write-down of GOCOVRI finished goods	$ 232,000	$ 0	$ 0

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies - Segments (Details)	12 Months Ended
	Dec. 31, 2018segment
Accounting Policies [Abstract]
Number of reportable segments	1

Basis of Presentation and Sum_6

Basis of Presentation and Summary of Significant Accounting Policies - Concentration of Risk (Details) - Customer One - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer
Concentration Risk [Line Items]
Concentration risk, percentage	99.00%
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	99.00%

Basis of Presentation and Sum_7

Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Computer equipment and software
Property and Equipment
Estimated useful lives of the assets	3 years
Equipment
Property and Equipment
Estimated useful lives of the assets	5 years
Furniture and fixtures
Property and Equipment
Estimated useful lives of the assets	10 years

Balance Sheet Components (Detai

Balance Sheet Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Prepaid expenses and other current assets
Prepaid expenses	$ 2,969	$ 2,638
Prepaid clinical trial	2,299	0
Income tax receivable	840	1,007
Other current assets	763	17
Prepaid expenses and other current assets	6,871	3,662
Property and equipment, gross	5,897	5,652
Less: Accumulated depreciation and amortization	(2,245)	(2,520)
Property and equipment, net	3,652	3,132
Depreciation expense	1,460	1,194	$ 808
Accrued liabilities
Accrued employee related costs	7,472	5,499
Clinical trial accruals	2,434	1,720
Accrued consulting and other professional fees	4,230	4,897
Current portion of long-term debt	1,664	0
Accrued sales deductions	1,053	91
Other	341	178
Accrued liabilities	17,194	12,385
Computer equipment and software
Prepaid expenses and other current assets
Property and equipment, gross	3,286	3,289
Equipment
Prepaid expenses and other current assets
Property and equipment, gross	384	252
Furniture and fixtures
Prepaid expenses and other current assets
Property and equipment, gross	336	466
Leasehold improvements
Prepaid expenses and other current assets
Property and equipment, gross	$ 1,891	$ 1,645

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Total assets measured at fair value	$ 172,054	$ 153,618
Liabilities:
Total liabilities measured at fair value	1,352	470
Level 1
Assets:
Total assets measured at fair value	17,789	68,501
Liabilities:
Total liabilities measured at fair value	0	0
Level 2
Assets:
Total assets measured at fair value	154,265	85,117
Liabilities:
Total liabilities measured at fair value	0	0
Level 3
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	1,352	470
Embedded derivative liability
Liabilities:
Total liabilities measured at fair value	1,352	470
Embedded derivative liability | Level 1
Liabilities:
Total liabilities measured at fair value	0	0
Embedded derivative liability | Level 2
Liabilities:
Total liabilities measured at fair value	0	0
Embedded derivative liability | Level 3
Liabilities:
Total liabilities measured at fair value	1,352	470
Money market
Assets:
Total assets measured at fair value	17,789	68,501
Money market | Level 1
Assets:
Total assets measured at fair value	17,789	68,501
Money market | Level 2
Assets:
Total assets measured at fair value	0	0
Money market | Level 3
Assets:
Total assets measured at fair value	0	0
Corporate debt
Assets:
Total assets measured at fair value	19,792	23,471
Corporate debt | Level 1
Assets:
Total assets measured at fair value	0	0
Corporate debt | Level 2
Assets:
Total assets measured at fair value	19,792	23,471
Corporate debt | Level 3
Assets:
Total assets measured at fair value	0	0
U.S. Treasury notes
Assets:
Total assets measured at fair value	131,512	61,646
U.S. Treasury notes | Level 1
Assets:
Total assets measured at fair value	0	0
U.S. Treasury notes | Level 2
Assets:
Total assets measured at fair value	131,512	61,646
U.S. Treasury notes | Level 3
Assets:
Total assets measured at fair value	0	$ 0
Commercial paper
Assets:
Total assets measured at fair value	2,961
Commercial paper | Level 1
Assets:
Total assets measured at fair value	0
Commercial paper | Level 2
Assets:
Total assets measured at fair value	2,961
Commercial paper | Level 3
Assets:
Total assets measured at fair value	$ 0

Fair Value Measurements - Rollf

Fair Value Measurements - Rollforward of Level 3 financial instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Fair vale Level 1 and 2 transfers	$ 0	$ 0
Fair vale Level 2 and 1 transfers	0	0
Level 3 | Long-term debt with embedded derivative
Roll forward of the financial instruments classified within Level 3 of the fair value hierarchy
Balance as of December 31, 2016	470,000	0
Issuance of long-term debt with embedded derivative		764,000
Change in fair value included in interest and other income, net	882,000	(294,000)
Balance as of December 31, 2018	$ 1,352,000	$ 470,000

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 154,529	$ 85,284
Gross Unrealized Gains	10	0
Gross Unrealized Losses	(274)	(167)
Fair Value	154,265	85,117
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	154,529	82,280
Gross Unrealized Gains	10	0
Gross Unrealized Losses	(274)	(154)
Fair Value	154,265	82,126
Accrued interest	500	600
Long-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	3,004
Gross Unrealized Losses	0	(13)
Fair Value	$ 0	2,991
Accrued interest		14
Long-term investments | Minimum
Debt Securities, Available-for-sale [Line Items]
Maturity range of long term investment	12 months
Corporate debt
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 19,833	23,507
Gross Unrealized Losses	(41)	(36)
Fair Value	19,792	23,471
U.S. Treasury notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	131,735	61,777
Gross Unrealized Gains	10	0
Gross Unrealized Losses	(233)	(131)
Fair Value	131,512	$ 61,646
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,961
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	$ 2,961

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 1,330	$ 859
Work-in-process	2,174	817
Finished goods	1,617	28
Total inventory	$ 5,121	$ 1,704

License Agreements (Details)

License Agreements (Details) - USD ($) $ in Thousands	Nov. 30, 2012	Dec. 31, 2014	May 31, 2014	Dec. 31, 2013	Dec. 31, 2018	Dec. 31, 2017
Collaboration and License Agreements
Final milestone payment received		$ 30,000
Period describing the commercial launch of dose					15 years
License agreement
Collaboration and License Agreements
Upfront payment received	$ 65,000
Maximum total additional cash payments receivable upon achievement of certain development and regulatory milestones	$ 95,000
Total milestone payments received				$ 40,000
Additional milestone payment received			$ 25,000
Prosecution and litigation cost					$ 1	$ 33

Commitments and Contingencies -

Commitments and Contingencies - Lease Commitments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jan. 31, 2018USD ($)ft²
Future minimum lease payments under the non-cancelable facility operating lease, non-cancelable purchase commitments, and annual minimum requirements
2,019	$ 6,064
2,020	3,733
2,021	3,406
2,022	3,468
2,023	2,181
Thereafter	3,011
Total	21,863
Emeryville, CA
Loss Contingencies [Line Items]
Operating lease, square footage (in sqft) | ft²				18,500
Operating lease, rentable square footage (in sqft) | ft²				37,626
Operating lease, tenet improvement allowance				$ 1,100
Rent expense	$ 1,200	$ 700	$ 600

Commitments and Contingencies_2

Commitments and Contingencies - Indemnification (Details)	Dec. 31, 2018claim
Commitments and Contingencies Disclosure [Abstract]
Number of indemnification claims	0

Commitments and Contingencies_3

Commitments and Contingencies - Litigation and Other Legal Proceedings (Details)	Dec. 31, 2018claim
Commitments and Contingencies Disclosure [Abstract]
Number of legal claims	0

Long-term Debt (Details)

Long-term Debt (Details) - USD ($)	1 Months Ended	3 Months Ended	7 Months Ended	12 Months Ended
	May 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Payment of debt issuance costs				$ 0	$ 633,000	$ 0
Level 3
Debt Instrument [Line Items]
Long-term debt, fair value				95,700,000
HCRP | Royalty-backed loan agreement
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 35,000,000	$ 65,000,000
Percentage revenue interest of future net sales	12.50%
Quarterly royalty payment (up to)	$ 15,000,000
Royalty percentage of future net sales	6.25%
Royalty trail cap, percentage of face amount	200.00%
Voluntary prepay election, amount due, percentage of funded amount	200.00%
Interest rate, stated percentage	11.00%
Contingent consideration, asset	$ 65,000,000
Unpaid interest payment added to principal amount, term	2 years 3 months
Lender expense		$ 400,000	$ 400,000		400,000
Payment of debt issuance costs			$ 800,000
Interest expense				$ 19,100,000	$ 4,600,000
Effective interest rate				14.50%
HCRP | Royalty-backed loan agreement | December 2021
Debt Instrument [Line Items]
Royalty percentage of future net sales if principal and interest payments below minimum specified levels (up to)	17.50%
HCRP | Royalty-backed loan agreement | December 2022
Debt Instrument [Line Items]
Royalty percentage of future net sales if principal and interest payments below minimum specified levels (up to)	22.50%

Long-term Debt - Long-Term Debt

Long-term Debt - Long-Term Debt and Unamortized Debt Discount Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Non-current portion of long-term debt	$ 117,457	$ 102,647
HCRP | Royalty-backed loan agreement
Debt Instrument [Line Items]
Total repayment obligation	200,000	200,000
Less: Interest to be accreted in future periods	(78,261)	(97,353)
Less: Payments made	(2,618)	0
Carrying value of loans payable	119,121	102,647
Less: Current portion of long-term debt	(1,664)	0
Non-current portion of long-term debt	$ 117,457	$ 102,647

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Apr. 15, 2014
Temporary Equity Disclosure [Abstract]
Preferred stock, authorized shares (in shares)	5,000,000	5,000,000	5,000,000
Preferred stock, outstanding shares (in shares)	0	0

Stockholders' Equity (Details)

Stockholders' Equity (Details)	1 Months Ended		12 Months Ended
	Jan. 31, 2018USD ($)$ / sharesshares	Jan. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2018USD ($)vote$ / sharesshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Nov. 30, 2017shares	May 31, 2017USD ($)	Jan. 31, 2017shares	Mar. 31, 2016shares
Shareholders' Equity
Authorized shares of common stock (in shares)			100,000,000	100,000,000
Dividends declared | $			$ 0
Number of votes per share | vote			1
Share price (in dollars per share) | $ / shares			$ 8.54
Proceeds from follow-on offering | $			$ 134,268,000	$ 0	$ 61,822,000
Number of shares available for future issuance under the plan (in shares)			9,123,160	8,170,939
2016 Inducement Plan
Shareholders' Equity
Number of shares available for future issuance under the plan (in shares)			512,440			1,350,000		900,000	450,000
Employee Stock Purchase Plan
Shareholders' Equity
Number of shares available for future issuance under the plan (in shares)			847,105	693,856
Cowen and Company, LLC
Shareholders' Equity
At-the-market offering, aggregate offering price (up to) | $							$ 50,000,000
At-the-market offering, commission as a percentage of gross proceeds (up to)							3.00%
Stock options
Shareholders' Equity
Number of shares available for future issuance under the plan (in shares)			5,949,436	5,564,635
Stock options | 2014 Equity Incentive Plan
Shareholders' Equity
Authorized for future issuance (in shares)			1,814,179	1,723,733
Stock options | 2016 Inducement Plan
Shareholders' Equity
Authorized for future issuance (in shares)			512,440	188,715
Common Stock
Shareholders' Equity
Common stock shares sold (in shares)	3,450,000	2,875,000	3,450,000		2,875,000
Share price (in dollars per share) | $ / shares	$ 41.50	$ 23
Proceeds from follow-on offering | $	$ 134,300,000	$ 61,800,000
Common Stock | Stock options | Over-Allotment Option
Shareholders' Equity
Common stock shares sold (in shares)	450,000	375,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Compensation Plans (Details) - shares	1 Months Ended			12 Months Ended
	Jan. 31, 2017	Mar. 31, 2016	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance under the plan (in shares)				9,123,160	8,170,939
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance under the plan (in shares)				5,949,436	5,564,635
2002 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for future grant or issuance (in shares)				0
2007 Stock Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for future grant or issuance (in shares)				0
2014 Equity Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for future grant or issuance (in shares)			1,993,394	1,814,179
Increase in common stock reserved for issuance as a percentage of total number of shares of the Company's capital stock outstanding on the last day of the preceding fiscal year			4.00%
Increase in common stock available for issuance (in shares)				932,822	880,362	739,708	701,763
Threshold ownership percentage of shareholder for determining exercise price of awards granted			10.00%
Vesting period			4 years
Vesting percentage on first anniversary of the issuance date			25.00%
Monthly vesting percentage of options after first anniversary of issuance date				2.08%
2014 Equity Incentive Plan | Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards			10 years
2014 Equity Incentive Plan | Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percentage of estimated fair value of the shares on the date of grant			100.00%
Exercise price as a percentage of estimated grant date fair value of shares for a 10% shareholder			110.00%
2014 Equity Incentive Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Award vesting rights percentage			25.00%
2016 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance under the plan (in shares)	900,000	450,000		512,440				1,350,000
Number of additional shares available for future issuance under the plan (in shares)	450,000
2016 Inducement Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Award vesting rights percentage		25.00%
2016 Inducement Plan | Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards		10 years
Vesting period		4 years
Vesting percentage on first anniversary of the issuance date		25.00%
Monthly vesting percentage of options after first anniversary of issuance date				2.08%
2016 Inducement Plan | Employee Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards		10 years

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Aggregate Intrinsic Value (thousands)
Fair value of common stock (in dollars per share)	$ 8.54
Stock options
Number of Shares
Balances, beginning of the period (in shares)	5,137,584
Options granted (in shares)	1,289,396
Options exercised (in shares)	(478,454)
Options forfeited (in shares)	(586,197)
Options expired (in shares)	(61,263)
Balances, end of the period (in shares)	5,301,066	5,137,584
Vested and expected to vest, end of the period (in shares)	5,179,804
Vested, end of the period (in shares)	3,599,021
Weighted Average Exercise Price
Balances, beginning of the period (in dollars per share)	$ 12.12
Options granted (in dollars per share)	25.27
Options exercised (in dollars per share)	7.03
Options forfeited (in dollars per share)	19.11
Options expired (in dollars per share)	14.97
Balances, end of the period (in dollars per share)	14.98	$ 12.12
Vested and expected to vest, end of the period (in shares)	14.81
Vested, end of the period (in shares)	$ 11.49
Weighted- Average Remaining Contractual Term (years)
Balances, end of the period	6 years 4 months
Vested and expected to vest, end of the period	6 years 3 months 10 days
Vested, end of the period	5 years 2 months 6 days
Aggregate Intrinsic Value (thousands)
Balances, end of the period	$ 6,525
Vested and expected to vest, end of the period	6,525
Vested, end of the period	6,525
Aggregate intrinsic value of exercises	$ 9,200	$ 18,100	$ 6,600
Employee Stock Options
Number of Shares
Options granted (in shares)	1,289,396	1,439,675	1,030,375
Aggregate Intrinsic Value (thousands)
Weighted-average grant date fair value (in dollars per share)	$ 16.08	$ 11.93	$ 9.15
Compensation not yet recognized	$ 22,100
Period for recognition of unrecognized compensation cost	2 years 9 months
Total fair value of awards vested	$ 12,100	$ 10,600	$ 8,400

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Unvested, Beginning balance (in shares)	427,051
Granted (in shares)	465,372
Vested (in shares)	(105,396)
Forfeited (in shares)	(138,657)
Unvested, Ending balance (in shares)	648,370	427,051
Weighted-Average Grant Date Fair Value
Unvested, Beginning balance (in dollars per share)	$ 18.72
Granted (in dollars per share)	16.05
Vested (in dollars per share)	18.39
Forfeited (in dollars per share)	20.07
Unvested, Ending balance (in dollars per share)	$ 16.57	$ 18.72
Aggregate intrinsic value, outstanding	$ 5,500,000
Aggregate intrinsic value, vested	2,300,000	$ 1,200,000	$ 0
Unrecognized compensation cost	$ 9,400,000
Period for recognition of unrecognized compensation cost	2 years 8 months

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plan (Details) - USD ($)	1 Months Ended	12 Months Ended				34 Months Ended
	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance under the plan (in shares)		9,123,160	8,170,939
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized for future issuance (in shares)	262,762
Exercise price as a percentage of estimated fair value of the shares on the date of grant	85.00%
Value of shares that an employee is permitted to purchase	$ 25,000
Stock issued under employee stock purchase plan (in shares)						229,320
Number of shares available for future issuance under the plan (in shares)		847,105
Increase in common stock available for issuance (in shares)		233,206	220,090	184,927	175,440
Employee Stock Purchase Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annual compensation of the employee to be deducted for purchase of shares	15.00%
Increase in common stock reserved for issuance as a percentage of total number of shares of the Company's capital stock outstanding on the last day of the preceding fiscal year	1.00%
Threshold number of shares to determine increase in common stock reserved for future issuance (in shares)	520,000

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 15,786	$ 13,367	$ 10,571
Stock-based compensation capitalized in inventory	202	39	0
Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	12,700	11,200	9,300
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	600	300	300
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,300	1,300	500
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,822	3,597	2,855
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 12,964	$ 9,770	$ 7,716

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Options
Assumptions to estimate the fair value of stock options
Expected price volatility, minimum	67.00%	68.00%	69.00%
Expected price volatility, maximum	70.00%	70.00%	71.00%
Risk-free interest rate, minimum	2.27%	1.83%	1.23%
Risk-free interest rate, maximum	3.06%	2.17%	1.81%
Dividend yield	0.00%	0.00%	0.00%
Employee Stock Options | Minimum
Assumptions to estimate the fair value of stock options
Expected term	5 years 6 months	5 years 6 months	5 years 6 months
Employee Stock Options | Maximum
Assumptions to estimate the fair value of stock options
Expected term	6 years 3 months	6 years 3 months	6 years 3 months
Employee Stock Purchase Plan
Assumptions to estimate the fair value of stock options
Expected price volatility, minimum	62.00%	51.00%	68.00%
Expected price volatility, maximum	64.00%	71.00%	73.00%
Risk-free interest rate, minimum	2.10%	0.60%	0.49%
Risk-free interest rate, maximum	2.56%	1.45%	0.60%
Expected term	6 months	6 months	6 months
Dividend yield	0.00%	0.00%	0.00%
Non-employee Stock Options
Assumptions to estimate non-employee stock options
Dividend yield	0.00%	0.00%	0.00%
Non-employee Stock Options | Minimum
Assumptions to estimate non-employee stock options
Expected price volatility	69.00%	68.00%	71.00%
Risk-free interest rate	2.32%	1.94%	1.47%
Expected term	6 years	6 years	7 years
Non-employee Stock Options | Maximum
Assumptions to estimate non-employee stock options
Expected price volatility	74.00%	80.00%	77.00%
Risk-free interest rate	2.45%	2.36%	2.46%
Expected term	9 years 6 months	9 years 9 months	9 years 9 months

Stock-Based Compensation - Non-

Stock-Based Compensation - Non-Employee Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 15,786	$ 13,367	$ 10,571
Non-employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	0	5,000	12,600
Stock-based compensation expense	$ 200	$ 600	$ 500
Non-employee Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	0	12,437

Income Taxes - Benefit for Inco

Income Taxes - Benefit for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income (loss) before provision for income tax
United States	$ (130,999)	$ (91,220)	$ (60,147)
International	0	0	(26)
Loss before income taxes	(130,999)	(91,220)	(60,173)
Current:
Federal	0	(1,730)	(116)
State	0	0	1
Benefit for income taxes	0	(1,730)	(115)
Difference of provision for income taxes from the amount computed by applying the federal income tax rate of 35% to pretax income from operations
Statutory federal income tax rate	(27,510)	(31,927)	(21,079)
State income taxes, net of federal tax benefits	(10,296)	(5,041)	(9)
Foreign rate differential	0	0	10
Tax credits	(2,587)	(2,306)	(3,905)
Impact of federal rate change	0	24,907	0
Change in statutory rates	34	(1,440)	624
Stock compensation	(569)	(2,558)	(1,109)
State net operating losses	0	633	1,779
Other	798	0	109
Change in valuation allowance	40,130	16,002	23,465
Benefit for income taxes	0	(1,730)	$ (115)
Significant components of the Company's deferred tax assets
Net operating loss carryforwards	75,143	44,177
Research and development tax credits	18,776	16,189
Accruals and reserves	4,655	371
Stock compensation	8,662	6,244
Depreciation and amortization	1,437	1,638
Other (rate change)	77	0
Total deferred tax assets	108,750	68,619
Less: Valuation allowance	(108,750)	(68,619)
Net deferred tax assets	$ 0	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating loss carryforwards
Federal income tax rate	21.00%
Increase in net valuation allowance	$ 40.1	$ 16
Deferred tax assets, tax credit carryforwards, alternative minimum tax	1.7
Research and development tax credit carryforward
Operating loss carryforwards
Tax credit carryforwards	14.4
Federal
Operating loss carryforwards
Net operating loss carryforwards	271.6	163.3
Federal | Research and development tax credit carryforward
Operating loss carryforwards
Tax credit carryforwards	5.2
State
Operating loss carryforwards
Net operating loss carryforwards	236.2	$ 131.3
State | Research and development tax credit carryforward
Operating loss carryforwards
Tax credit carryforwards	$ 3.9

Income Taxes - Uncertain Tax Po

Income Taxes - Uncertain Tax Positions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits that would impact effective tax rate	$ 0
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at the beginning of the year	4,034,000	$ 3,188,000	$ 1,820,000
Additions based on prior period tax positions	220,000	43,000	93,000
Additions based on current period tax positions	443,000	803,000	1,275,000
Balance at the end of the year	4,697,000	4,034,000	3,188,000
Interest related to unrecognized tax benefits	0	$ 0	$ 0
Tax Cuts and Jobs Act of 2017, incomplete accounting, change in tax rate, deferred tax liability, provisional income tax benefit	24,900,000
Tax Cuts and Jobs Act of 2017, incomplete accounting, transition tax for AMT credits, provisional income tax benefit	$ 1,700,000

Net Loss per Share (Details)

Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net loss	$ (28,883)	$ (33,152)	$ (33,993)	$ (34,971)	$ (29,357)	$ (23,360)	$ (20,745)	$ (16,028)	$ (130,999)	$ (89,490)	$ (60,058)
Weighted average common shares used in calculating net loss per share, basic and diluted (in shares)									26,886	22,558	21,711
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.06)	$ (1.22)	$ (1.26)	$ (1.35)	$ (1.27)	$ (1.04)	$ (0.93)	$ (0.72)	$ (4.87)	$ (3.97)	$ (2.77)
Anti-dilutive securities
Anti-dilutive securities (in shares)									5,949	5,565	5,483
Options to purchase common stock
Anti-dilutive securities
Anti-dilutive securities (in shares)									5,301	5,138	5,270
Restricted stock units
Anti-dilutive securities
Anti-dilutive securities (in shares)									648	427	213

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 13,315	$ 10,613	$ 7,565	$ 2,553	$ 568	$ 1	$ 2	$ 0	$ 34,046	$ 571	$ 572
Gross profit	12,880	10,513	7,492	2,528	551	0	0	0
Net loss	$ (28,883)	$ (33,152)	$ (33,993)	$ (34,971)	$ (29,357)	$ (23,360)	$ (20,745)	$ (16,028)	$ (130,999)	$ (89,490)	$ (60,058)
Net loss per share, basic and diluted (in dollars per share)	$ (1.06)	$ (1.22)	$ (1.26)	$ (1.35)	$ (1.27)	$ (1.04)	$ (0.93)	$ (0.72)	$ (4.87)	$ (3.97)	$ (2.77)