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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2017	Mar. 09, 2018	Jun. 30, 2017
Document Entity Information [Abstract]
Entity Registrant Name	Minerva Neurosciences, Inc.
Entity Central Index Key	0001598646
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 238.6
Entity Common Stock, Shares Outstanding		38,749,343
Trading Symbol	NERV

Consolidated Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 26,051,821	$ 82,980,609
Marketable securities	102,109,419
Restricted cash	80,000	80,000
Prepaid expenses and other current assets	1,299,184	803,241
Total current assets	129,540,424	83,863,850
Marketable securities - noncurrent	5,022,982
Equipment, net	50,945	9,640
Other noncurrent assets	14,808
In-process research and development	34,200,000	34,200,000
Goodwill	14,869,399	14,869,399
Total assets	183,698,558	132,942,889
Current liabilities
Notes payable -current portion	3,962,664	4,853,753
Accounts payable	1,435,636	1,468,341
Accrued expenses and other current liabilities	1,439,848	815,813
Accrued collaborative expenses - related party		2,547,952
Total current liabilities	6,838,148	9,685,859
Notes payable - noncurrent		3,841,062
Deferred taxes	4,057,488	13,433,760
Deferred revenue	41,175,600
Other noncurrent liabilities	29,878
Total liabilities	52,101,114	26,960,681
Commitments and contingencies
Stockholders’ equity
Preferred stock; $.0001 par value; 100,000,000 shares authorized; none issued or outstanding as of December 31, 2017 and 2016, respectively
Common stock; $.0001 par value; 125,000,000 shares authorized; 38,749,343 and 35,024,002 shares issued and outstanding as of December 31, 2017 and 2016, respectively	3,875	3,502
Additional paid-in capital	295,975,010	238,836,940
Accumulated deficit	(164,381,441)	(132,858,234)
Total stockholders’ equity	131,597,444	105,982,208
Total liabilities and stockholders’ equity	$ 183,698,558	$ 132,942,889

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	38,749,343	35,024,002
Common stock, shares outstanding	38,749,343	35,024,002

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expenses
Research and development	$ 30,255,892	$ 20,439,994	$ 18,533,363
General and administrative	10,914,269	9,750,702	7,576,256
Total expenses	41,170,161	30,190,696	26,109,619
Loss from operations	(41,170,161)	(30,190,696)	(26,109,619)
Foreign exchange losses	(56,887)	(23,395)	(15,853)
Investment income	941,833	198,453	96,910
Interest expense	(614,264)	(1,029,734)	(1,053,070)
Loss before income taxes	(40,899,479)	(31,045,372)	(27,081,632)
Benefit for income taxes	(9,376,272)	0	0
Net loss	$ (31,523,207)	$ (31,045,372)	$ (27,081,632)
Net loss per share, basic and diluted	$ (0.83)	$ (0.99)	$ (1.16)
Weighted average shares outstanding, basic and diluted	37,937,191	31,514,154	23,412,181

Consolidated Statements of Stockholders' Equity - USD ($)	Total	Private Placement	Public Offering	Common Stock	Common Stock Private Placement	Common Stock Public Offering	Additional Paid-in Capital	Additional Paid-in Capital Private Placement	Additional Paid-in Capital Public Offering	Accumulated Deficit
Balance at Dec. 31, 2014	$ 51,499,595			$ 1,844			$ 126,228,981			$ (74,731,230)
Balance (in shares) at Dec. 31, 2014				18,439,482
Issuance of common stock and warrants, net of issuance costs		$ 28,533,015			$ 628			$ 28,532,387
Issuance of common stock and warrants, net of issuance costs (in shares)					6,281,661
Exercise of stock options (in shares)	0
Issuance of warrants pursuant to loan agreement	$ 166,344						166,344
Stock-based compensation	2,202,235						2,202,235
Net loss	(27,081,632)									(27,081,632)
Balance at Dec. 31, 2015	55,319,557			$ 2,472			157,129,947			(101,812,862)
Balance (in shares) at Dec. 31, 2015				24,721,143
Issuance of common stock and warrants, net of issuance costs		$ 999,999	$ 53,667,991		$ 18	$ 606		$ 999,981	$ 53,667,385
Issuance of common stock and warrants, net of issuance costs (in shares)					181,488	6,052,631
Exercise of common stock warrants	23,392,098			$ 405			23,391,693
Exercise of common stock warrants (in shares)				4,052,685
Exercise of stock options	76,724			$ 1			76,723
Exercise of stock options (in shares)				16,055
Stock-based compensation	3,571,211						3,571,211
Net loss	(31,045,372)									(31,045,372)
Balance at Dec. 31, 2016	$ 105,982,208			$ 3,502			238,836,940			(132,858,234)
Balance (in shares) at Dec. 31, 2016	35,024,002			35,024,002
Repurchase of common stock	$ (389)			$ (389)
Repurchase of common stock (in shares)				(3,892,256)
Issuance of common stock and warrants, net of issuance costs			$ 41,618,332			$ 575			$ 41,617,757
Issuance of common stock and warrants, net of issuance costs (in shares)						5,750,000
Exercise of common stock warrants	9,356,833			$ 162			9,356,671
Exercise of common stock warrants (in shares)				1,621,073
Exercise of stock options	1,130,544			$ 20			1,130,524
Exercise of stock options (in shares)				197,874
Vesting of restricted stock units				$ 5			(5)
Vesting of restricted stock units (in shares)				48,650
Stock-based compensation	5,033,123						5,033,123
Net loss	(31,523,207)									(31,523,207)
Balance at Dec. 31, 2017	$ 131,597,444			$ 3,875			$ 295,975,010			$ (164,381,441)
Balance (in shares) at Dec. 31, 2017	38,749,343			38,749,343

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Public Offering
Issuance cost	$ 2,944,168	$ 3,832,004

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (31,523,207)	$ (31,045,372)	$ (27,081,632)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11,094	16,530	17,276
Amortization of debt discount recorded as interest expense	206,562	347,771	377,455
(Accretion) amortization of marketable securities premium	(185,488)	102,632	247,262
Stock-based compensation expense	5,033,123	3,571,211	2,202,235
Deferred taxes	(9,376,272)
Changes in operating assets and liabilities
Prepaid expenses and other current assets	(306,996)	372,655	(400,037)
Accounts payable	(32,705)	107,772	718,756
Accrued expenses and other current liabilities	624,035	(1,708,825)	879,380
Accrued collaborative expenses	(2,547,952)	2,547,952	(1,222,420)
Deferred revenue	41,175,600
Other noncurrent assets	(14,808)
Other noncurrent liabilities	29,878		(7,694)
Net cash provided by (used in) operating activities	3,092,864	(25,687,674)	(24,269,419)
Cash flows from investing activities:
Purchases of marketable securities	(134,525,859)		(23,279,285)
Proceeds from the maturity and redemption of marketable securities	27,390,000	17,818,000	4,994,683
Restricted cash			(44,986)
Purchases of equipment	(52,400)
Net cash (used in) provided by investing activities	(107,188,259)	17,818,000	(18,329,588)
Cash flows from financing activities:
Proceeds from sale of common stock in public offering	44,562,500	57,499,995
Costs paid in connection with public offering	(2,944,168)	(3,832,004)
Repurchase of common stock	(389)
Proceeds from sales of common stock in private placement		999,999	30,999,999
Costs paid in connection with private placements			(2,466,984)
Proceeds from exercise of common stock warrants	9,356,833	23,392,098
Proceeds from exercise of stock options	1,130,544	76,724
Proceeds from notes payable			10,000,000
Costs paid in connection with notes payable			(195,656)
Repayments of notes payable	(4,938,713)	(1,570,583)
Net cash provided by financing activities	47,166,607	76,566,229	38,337,359
Net (decrease) increase in cash and cash equivalents	(56,928,788)	68,696,555	(4,261,648)
Cash and cash equivalents
Beginning of year	82,980,609	14,284,054	18,545,702
End of year	26,051,821	82,980,609	14,284,054
Supplemental disclosure
Cash paid for interest	$ 436,717	$ 691,227	$ 616,875

Nature of Operations and Liquidity	12 Months Ended
Nature of Operations and Liquidity	Dec. 31, 2017
Nature Of Operations And Liquidity Disclosure [Abstract]
Nature of Operations and Liquidity	NOTE 1 — NATURE OF OPERATIONS AND LIQUIDITY Nature of Operations Minerva Neurosciences, Inc. (“Minerva” or the “Company”) is a clinical-stage biopharmaceutical company focused on the development and commercialization of a portfolio of product candidates to treat patients suffering from central nervous system, or CNS, diseases. The Company has acquired or in-licensed four development-stage proprietary compounds that it believes have innovative mechanisms of action and therapeutic profiles that may potentially address the unmet needs of patients with these diseases. The Company’s lead product candidate is roluperidone (also known as MIN-101), a compound the Company is developing for the treatment of schizophrenia. In addition, the Company’s portfolio includes seltorexant (also known as MIN-202 or JNJ-42847922), a compound the Company is co-developing with Janssen Pharmaceutica NV (“Janssen”) for the treatment of insomnia disorder and major depressive disorder (“MDD”); MIN-117, a compound the Company is developing for the treatment of MDD; and MIN-301, a compound the Company is developing for the treatment of Parkinson’s disease. In November 2013, the Company merged with Sonkei Pharmaceuticals Inc. (“Sonkei”), a clinical-stage biopharmaceutical company and, in February 2014, the Company acquired Mind-NRG, a pre-clinical-stage biopharmaceutical company. The Company refers to these transactions as the Sonkei Merger and Mind-NRG Acquisition, respectively. The Company holds licenses to roluperidone and MIN-117 from Mitsubishi Tanabe Pharma Corporation (“MTPC”) with the rights to develop, sell and import roluperidone and MIN-117 globally, excluding most of Asia. With the acquisition of Mind-NRG, the Company obtained exclusive rights to develop and commercialize MIN-301. The Company has also entered into a co-development and license agreement with Janssen, for the exclusive right to commercialize, and the co-exclusive right (with Janssen and its affiliates) to use and develop, seltorexant in the European Union, Switzerland, Liechtenstein, Iceland and Norway (the “Minerva Territory”), subject to certain royalty payments to Janssen, and royalty rights for any sales outside the Minerva Territory. Liquidity The accompanying financial statements have been prepared as though the Company will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The Company has limited capital resources and has incurred recurring operating losses and negative cash flows from operations since inception. As of December 31, 2017, the Company has an accumulated deficit of approximately $164.4 million and net cash provided by operating activities was approximately $3.1 million during the year ended December 31, 2017. Management expects to continue to incur operating losses and negative cash flows from operations. The Company has financed its operations to date from proceeds from the sale of common stock, warrants, loans and convertible promissory notes. As of December 31, 2017, the Company had cash, cash equivalents and marketable securities (current and non-current) of $133.2 million. During the year ended December 31, 2017, the Company received approximately $41.6 million in net proceeds from a July 2017 public offering of common stock (see Note 7), proceeds from the exercise of common stock warrants of $9.4 million (see Note 7) and $30 million in an upfront payment in connection with the Company’s amended Co-Development and License Agreement with Janssen for seltorexant (see Note 6). The Company believes that its existing cash, cash equivalents and marketable securities (current and non-current) will be sufficient to meet its cash commitments for at least the next 12 months after the date that the financial statements are issued. The process of drug development can be costly and the timing and outcomes of clinical trials is uncertain. The assumptions upon which the Company has based its estimates are routinely evaluated and may be subject to change. The actual amount of the Company’s expenditures will vary depending upon a number of factors including but not limited to the design, timing and duration of future clinical trials, the progress of the Company’s research and development programs and the level of financial resources available. The Company has the ability to adjust its operating plan spending levels based on the timing of future clinical trials which will be predicated upon adequate funding to complete the trials. The Company will need to raise additional capital in order to continue to fund operations and fully fund later stage clinical development programs. The Company believes that it will be able to obtain additional working capital through equity financings or other arrangements to fund future operations; however, there can be no assurance that such additional financing, if available, can be obtained on terms acceptable to the Company. If the Company is unable to obtain such additional financing, future operations would need to be scaled back or discontinued.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

NOTE 2 — SIGNIFICANT ACCOUNTING POLICIES

Basis of presentation

The financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. From its inception, the Company has devoted substantially all of its efforts to business planning, engaging regulatory, manufacturing and other technical consultants, planning and executing clinical trials and raising capital.

Consolidation

The accompanying consolidated financial statements include the results of the Company and its wholly-owned subsidiaries, Mind-NRG Sarl and Minerva Neurosciences Securities Corporation. Intercompany transactions have been eliminated.

Significant risks and uncertainties

The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to: the results of clinical testing and trial activities of the Company’s products, the Company’s ability to obtain regulatory approval to market its products, competition from products manufactured and sold or being developed by other companies, the price of, and demand for, Company products, the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products, and the Company’s ability to raise capital.

The Company currently has no commercially approved products and there can be no assurance that the Company’s research and development will be successfully commercialized. Developing and commercializing a product requires significant time and capital and is subject to regulatory review and approval as well as competition from other biotechnology and pharmaceutical companies. The Company operates in an environment of rapid change and is dependent upon the continued services of its employees and consultants and obtaining and protecting intellectual property.

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Cash and cash equivalents

Cash equivalents include short-term, highly-liquid instruments, consisting of money market accounts and short-term investments with maturities from the date of purchase of 90 days or less. The majority of cash and cash equivalents are maintained with major financial institutions in North America. Deposits with these financial institutions may exceed the amount of insurance provided on such deposits. These deposits may be redeemed upon demand which reduces counterparty performance risk.

Restricted cash

Cash accounts with any type of restriction are classified as restricted. The Company maintained restricted cash balances as collateral for corporate credit cards in the amount of $80,000 at December 31, 2017 and 2016.

Marketable securities

Marketable securities consists of corporate debt securities maturing in sixteen months or less. Based on the Company’s intentions regarding its marketable securities, all marketable securities are classified as held-to-maturity and are carried under the amortized cost approach. The Company’s investments in marketable securities are classified as Level 2 within the fair value hierarchy. As of December 31, 2017, remaining final maturities of marketable securities ranged from January 2018 to February 2019, with a weighted average remaining maturity of approximately 4.79 months. The following table provides the amortized cost basis, aggregate fair value, net unrealized (gains)/losses and the net carrying value of investments in held-to-maturity securities as of December 31, 2017:

	December 31, 2017
	Amortized		Aggregate		Unrealized		Unrealized		Net Carrying
	Cost		Fair Value		Gains		Losses		Value
Marketable securities current:
Corporate bonds/notes	$	43,528,246	$	43,438,463	$	89,783	$	—	$	43,528,246
Commercial paper		43,385,762		43,385,762		—		—		43,385,762
U.S. government agency securities		15,195,411		15,178,278		17,133		—		15,195,411
Marketable securities current total		102,109,419		102,002,503		106,916		—		102,109,419

Marketable securities non-current:
Corporate bonds/notes		5,022,982		4,998,870		24,112		—		5,022,982
Commercial paper		—		—		—		—		—
U.S. government agency securities		—		—		—		—		—
Marketable securities non-current total		5,022,982		4,998,870		24,112		—		5,022,982

Marketable securities total	$	107,132,401	$	107,001,373	$	131,028	$	—	$	107,132,401

Research and development costs

Costs incurred in connection with research and development activities are expensed as incurred. These costs include licensing fees to use certain technology in the Company’s research and development projects as well as fees paid to consultants and various entities that perform certain research and testing on behalf of the Company and costs related to salaries, benefits, bonuses and stock-based compensation granted to employees in research and development functions. The Company determines expenses related to clinical studies based on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and contract research organizations that conduct and manage clinical studies on its behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the accrual is adjusted accordingly. The expenses for some trials may be recognized on a straight-line basis if the expected costs are expected to be incurred ratably during the period. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued expenses.

In-process research and development

In-process research and development (“IPR&D”) assets represent capitalized incomplete research projects that the Company acquired through business combinations. Such assets are initially measured at their acquisition date fair values. The initial fair value of the research projects are recorded as intangible assets on the balance sheet, rather than expensed, regardless of whether these assets have an alternative future use.

The amounts capitalized are being accounted for as indefinite-lived intangible assets, subject to impairment testing, until completion or abandonment of research and development efforts associated with the project. An IPR&D asset is considered abandoned when it ceases to be used (that is, research and development efforts associated with the asset have ceased, and there are no plans to sell or license the asset or derive defensive value from the asset). At that point, the asset is considered to be disposed of and is written off. Upon successful completion of each project, the Company will make a determination about the then remaining useful life of the intangible asset and begin amortization. The Company tests its indefinite-lived intangibles, IPR&D assets, for impairment annually on November 30 and more frequently if events or changes in circumstances indicate that it is more likely than not that the asset is impaired. When testing indefinite-lived intangibles for impairment, the Company may assess qualitative factors for its indefinite-lived intangibles to determine whether it is more likely than not (that is, a likelihood of more than 50 percent) that the asset is impaired. Alternatively, the Company may bypass this qualitative assessment for some or all of its indefinite-lived intangibles and perform the quantitative impairment test that compares the fair value of the indefinite-lived intangible asset with the asset’s carrying amount. There was no impairment of IPR&D for the years ended December 31, 2017 or 2016.

Stock-based compensation

The Company recognizes compensation cost relating to stock-based payment transactions using a fair-value measurement method, which requires all stock-based payments to employees, including grants of employee stock options, to be recognized in operating results as compensation expense based on fair value over the requisite service period of the awards. The Company determines the fair value of stock-based awards using the Black-Scholes option-pricing model which uses both historical and current market data to estimate fair value. The method incorporates various assumptions such as the risk-free interest rate, expected volatility, expected dividend yield, expected forfeiture rate and expected life of the options. The fair value of restricted stock units (“RSU’s”) is equal to the closing price of the Company’s common stock on the date of grant.

The date of expense recognition for grants to non-employees is the earlier of the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or the date at which the counterparty’s performance is complete. The Company determines the fair value of stock-based awards granted to non-employees similar to the way fair value of awards are determined for employees except that certain assumptions used in the Black-Scholes option-pricing model, such as expected life of the option, may be different and the fair value of each unvested award is adjusted at the end of each period for any change in fair value from the previous valuation until the award vests.

Foreign currency transactions

The Company’s functional currency is the US dollar. The Company pays certain vendor invoices in the respective foreign currency. The Company records an expense in US dollars at the time the liability is incurred. Changes in the applicable foreign currency rate between the date an expense is recorded and the payment date is recorded as a foreign currency gain or loss.

Loss per share

Basic loss per share is computed by dividing net loss by the weighted-average number of shares of common stock outstanding for the period. Diluted loss per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that shared in the earnings of the entity. The treasury stock method is used to determine the dilutive effect of the Company’s stock options and warrants. The Company had a net loss in all periods presented thus the inclusion of stock options and warrants would be anti-dilutive to net loss per share.

Income taxes

Deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Uncertain tax positions are evaluated and if appropriate, the amount of unrecognized tax benefits are recorded within deferred tax assets. Deferred tax assets are evaluated for realization based on a more-likely-than-not criterion in determining if a valuation allowance should be provided. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

The Company uses a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken, or expected to be taken, in a tax return. The Company has elected to treat interest and penalties, to the extent they arise, as a component of income tax expense. There was no interest or penalties related to income taxes for the years ended December 31, 2017, 2016 or 2015. Income tax years beginning in 2012 for federal and state purposes are generally subject to examination by taxing authorities, although net operating losses from all prior years are subject to examinations and adjustments for at least three years following the year in which the tax attributes are utilized.

On December 22, 2017, the United States enacted tax reform legislation commonly known as the Tax Cuts and Jobs Act (the “Act”), resulting in significant modifications to existing law. The Company has completed the accounting for the effects of the Act during 2017. The Company’s financial statements for the year ended December 31, 2017, reflect the effects of the Act which includes a reduction in the corporate tax rate from 34% to 21%. Accordingly, the Company’s deferred tax assets and liabilities were revalued at the newly enacted rates expected to be effective in 2018 and forward; the reduction in federal rate from 34% to 21% resulted in no impact to total income tax expense. In addition to the federal rate change impact, the Company accounted for the impact of legislation on the timing of deferred tax positions and overall financial statement presentation, resulting in a total income tax benefit of $9.4 million related to future implications of indefinite lived deferred tax positions.

Concentration of credit risk

Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and marketable securities (current and non-current). The Company maintains its cash and cash equivalent balances in the form of business checking accounts and money market accounts, the balances of which, at times, may exceed federally insured limits. Exposure to cash and cash equivalents credit risk is reduced by placing such deposits with major financial institutions and monitoring their credit ratings. Marketable securities consist primarily of corporate bonds, with fixed interest rates. Exposure to credit risk of marketable securities is reduced by maintaining a diverse portfolio and monitoring their credit ratings.

Equipment

Equipment is stated at cost less accumulated depreciation. Equipment is depreciated on the straight-line basis over their estimated useful lives of three years. Expenditures for maintenance and repairs are charged to expense as incurred.

Long-lived assets

The Company reviews the recoverability of all long-lived assets, including the related useful lives, whenever events or changes in circumstances indicate that the carrying amount of a long-lived asset might not be recoverable. If required, the Company compares the estimated undiscounted future net cash flows to the related asset’s carrying value to determine whether there has been an impairment. If an asset is considered impaired, the asset is written down to fair value, which is based either on discounted cash flows or appraised values in the period the impairment becomes known. The Company believes that all long-lived assets are recoverable, and no impairment was deemed necessary at December 31, 2017 and 2016.

Goodwill

The Company tests its goodwill for impairment annually, or whenever events or changes in circumstances indicate an impairment may have occurred, by comparing its reporting unit’s carrying value to its fair value. Impairment may result from, among other things, deterioration in the performance of the acquired business, adverse market conditions, adverse changes in applicable laws or regulations and a variety of other circumstances. If the Company determines that an impairment has occurred, it is required to record a write-down of the carrying value and charge the impairment as an operating expense in the period the determination is made. In evaluating the recoverability of the carrying value of goodwill, the Company must make assumptions regarding estimated future cash flows and other factors to determine the fair value of the acquired assets. Changes in strategy or market conditions could significantly impact those judgments in the future and require an adjustment to the recorded balances. The Company tested its goodwill for impairment as of November 30. There was no impairment of goodwill for the years ended December 31, 2017 or 2016.

Fair value of financial instruments

The Company provides disclosure of financial assets and financial liabilities that are carried at fair value based on the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurements may be classified based on the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities using the following three levels:

Level 1 — Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2 — Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.) and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

Level 3 — Unobservable inputs that reflect the Company’s estimates of the assumptions that market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available, including its own data.

The following tables present information about the Company’s cash equivalents and marketable securities (current and non-current) as of December 31, 2017 and 2016, measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value:

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	22,782,626	$	22,782,626	$	—	$	—
Marketable securities		107,132,401		—		107,132,401		—
Total fair value	$	129,915,027	$	22,782,626	$	107,132,401	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	15,260,809	$	15,260,809	$	—	$	—

Marketable securities are valued using models or other valuation methodologies that use Level 2 inputs. These models are primarily industry-standard models that consider various assumptions, including time value, yield curve, volatility factors, default rates, current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace.

The carrying amounts of cash, restricted cash, accounts payable, and accrued liabilities approximate fair value because of their short-term nature. The Company believes that the Company's debt obligations accrue interest at rates which approximate prevailing market rates for instruments with similar characteristics and, accordingly, the carrying values for these instruments approximate fair value.

Revenue recognition

The Company applies the revenue recognition guidance in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 605, Revenue Recognition. Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title has passed, the price is fixed or determinable, and collectability is reasonably assured. The Company is a development stage company and has had no revenues from product sales to date.

When the Company enters into an arrangement that meets the definition of a collaboration under ASC 808, Collaboration Arrangements, the Company recognizes revenue as the research and development is performed and its respective share of the expenses are incurred. The Company assesses whether the arrangement contains multiple elements or deliverables, which may include (1) licenses to the Company's technology, (2) research and development activities performed for the collaboration partner, and (3) participation on Joint Steering Committees. Payments may include non-refundable, upfront payments, milestone payments upon achieving significant development events, and royalties on future sales. Each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has “stand-alone value” to the customer. The arrangement’s consideration is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The estimated selling price of each deliverable is determined using the following hierarchy of values: (i) vendor-specific objective evidence of fair value; (ii) third-party evidence of selling price; and (iii) best estimate of selling price. The best estimate of selling price reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold by the Company on a stand-alone basis. The consideration allocated to each unit of accounting is then recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Supply or service transactions may involve the charge of a nonrefundable initial fee with subsequent periodic payments for future products or services. The up-front fees, even if nonrefundable, are recognized as revenue as the products and/or services are delivered and performed over the term of the arrangement.

Deferred revenue

The Company applies the revenue recognition guidance in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 605, Revenue Recognition. Using FASB ASC 605, Revenue that is unearned is deferred. Deferred revenue expected to be recognized as revenue more than one year subsequent to the balance sheet date is classified as long-term deferred revenue.

Segment information

Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) about which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief decision maker, who is the Chief Executive Officer, reviews operating results to make decisions about allocating resources and assessing performance for the entire Company. The Company views its operations and manages its business as one operating segment.

Comprehensive loss

The Company had no items of comprehensive loss other than its net loss for each period presented.

Recent accounting pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) and are adopted by the Company as of the specified effective date.

Recently Adopted Accounting Pronouncements

In March 2016, the FASB issued Accounting Standards Update (“ASU”) No 2016-09, Compensation – Stock Compensation (Topic 718). The new standard simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. Under this guidance, a company recognizes all excess tax benefits and tax deficiencies as income tax expense or benefit in the statement of operations. This change eliminates the notion of the additional paid-in capital pool and reduces the complexity in accounting for excess tax benefits and tax deficiencies. The new standard is effective for public companies for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods; however, early adoption is allowed. The Company adopted the new standard on January 1, 2017. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

Accounting Pronouncements Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”). Subsequently, the FASB also issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606) , which adjusted the effective date of ASU 2014-09; ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) , which amends the principal-versus-agent implementation guidance and illustrations in ASU 2014-09; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing , which clarifies identifying performance obligation and licensing implementation guidance and illustrations in ASU 2014-09; and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients , which addresses implementation issues and is intended to reduce the cost and complexity of applying the new revenue standard in ASU 2014-09 (collectively, the “Revenue ASUs”).

The Revenue ASUs provide an accounting standard for a single comprehensive model for use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2017, with an option to early adopt for interim and annual periods beginning after December 15, 2016. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (the full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). The Company performed a detailed review of its collaboration agreements and assessed the differences in accounting for such contracts under this guidance compared with current revenue accounting standards. Based on its review of the collaboration agreements, adoption of the new standard is not expected to have a material impact on the Company’s consolidated financial statements. The Company will adopt the new standard on January 1, 2018 using the modified retrospective method.

In February 2016, the FASB issued ASU No 2016-02, Leases. The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. Although the Company is currently assessing the impact of adoption of ASU 2016-02 on its consolidated financial statements, the Company currently believes the most significant changes will be related to the recognition of new right-of-use assets and lease liabilities on the Company’s balance sheet for operating leases. Refer to Note 10, Commitments and Contingencies, for the Company's current lease commitments.

In August 2016, the FASB issued ASU No 2016-15, Statement of Cash Flows – Classification of Certain Cash Receipts and Cash Payments (Topic 230). The new standard clarifies the treatment of several cash flow categories. In addition, ASU 2016-15 clarifies that when cash receipts and cash payments have aspects of more than one class of cash flows and cannot be separated, classification will depend on the predominant source or use. This update is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted, including adoption in an interim period. The Company is currently evaluating the impact of the pending adoption of the new standard on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU No 2017-4, Intangibles — Goodwill and Other (Topic 350). The new standard simplifies the Test for Goodwill Impairment. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted, including adoption in an interim period. The Company is currently evaluating the impact of the pending adoption of the new standard on the Company’s consolidated financial statements.

In March 2017, the FASB issued ASU No 2017-8, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20) Premium Amortization on Purchased Callable Debt Securities. The new standard is intended to enhance the accounting for the amortization of premiums for purchased callable debt securities. This update is effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted, including adoption in an interim period. The Company is currently evaluating the impact of the pending adoption of the new standard on the Company’s consolidated financial statements.

Accrued Expenses and Other Liabilities

12 Months Ended

Dec. 31, 2017

Payables And Accruals [Abstract]

Accrued Expenses and Other Liabilities

NOTE 3 — ACCRUED EXPENSES AND OTHER LIABILITIES

Accrued expenses and other liabilities consist of the following:

	December 31, 2017		December 31, 2016
Research and development costs and other accrued expenses	$	1,162,441	$	574,290
Professional fees		251,000		192,000
Interest payable		20,508		49,523
Accrued bonus		5,899		—
	$	1,439,848	$	815,813

Net Loss Per Share of Common Stock

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Net Loss Per Share of Common Stock

NOTE 4 — NET LOSS PER SHARE OF COMMON STOCK

Diluted loss per share is the same as basic loss per share for all periods presented as the effects of potentially dilutive items were anti-dilutive given the Company’s net loss. Basic loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding. The following table sets forth the computation of basic and diluted loss per share for common stockholders:

	Year Ended December 31,
	2017			2016			2015
Net loss	$	(31,523,207	)	$	(31,045,372	)	$	(27,081,632	)
Weighted average shares of common stock outstanding		37,937,191			31,514,154			23,412,181
Net loss per share of common stock – basic and diluted	$	(0.83	)	$	(0.99	)	$	(1.16	)

The following securities outstanding at December 31, 2017, 2016 and 2015 have been excluded from the calculation of weighted average shares outstanding as their effect on the calculation of loss per share is antidilutive:

	December 31, 2017		December 31, 2016		December 31, 2015
Common stock options		6,132,650		3,974,143		3,388,698
Restricted stock units		185,950		219,600		—
Common stock warrants		40,790		2,269,766		6,322,451

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

NOTE 5 — DEBT

Loan and Security Agreement

On January 16, 2015, the Company entered into a Loan and Security Agreement (as amended the “Loan Agreement”) with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB” and, together with Oxford, the “Lenders”), providing for term loans to the Company in an aggregate principal amount of up to $15 million, in two tranches (the “Term Loans”).

The Company drew down the initial term loans in the aggregate principal amount of $10 million (the “Term A Loans”), on January 16, 2015. The Term A Loans bear interest at a fixed rate of 7.05% per annum. The Company believes that the Company's debt obligations accrue interest at rates which approximate prevailing market rates for instruments with similar characteristics and, accordingly, the carrying values for these instruments approximate fair value.

In August 2015, the Lenders and the Company entered into a First Amendment to the Loan Agreement, amending certain milestones related to the six month extension of the interest-only repayment period. By raising at least $30.0 million in gross capital (including at least $20.0 million from the sale of equity securities) and completing the first dosing of its Phase I/II clinical trial for MIN-117 prior to December 31, 2015, the Company achieved the interest-only milestones under the Loan Agreement and elected to extend the interest-only period an additional six months and reduce the repayment term by six months. Through August 1, 2016, the Company was obligated only to make monthly interest payments on the outstanding principal balance on the Term A Loans, followed by 24 months of equal principal and interest payments.

On or prior to March 31, 2016, the Company was permitted to borrow additional term loans in the aggregate principal amount up to $5 million, subject to the satisfaction of certain borrowing conditions, including the Company’s achievement of primary endpoints on its Phase IIa trials for MIN-117 and seltorexant programs. In June 2016, the Company irrevocably elected not to borrow the additional $5 million available under the Term Loans.

The Company paid a facility fee of $75,000 for access to the Term Loans and will be required to pay a final payment of 5.1% of the total amount borrowed, which has been included as a component of the debt discount and is amortized to interest expense over the term of the loans. The outstanding Term A Loans and debt discount are as follows:

	December 31, 2017
Term A Loans	$	3,490,704
Less: debt discount and financing costs		(15,550	)
Less: current portion		(3,962,664	)
Accrued portion of final payment		487,510
Long-term portion	$	—

For the year ended December 31, 2017, and 2016, the Company recognized interest expense of $0.6 million and $1.0 million, respectively, including $0.2 million and $0.3 million, respectively, related to the debt discount.

The Term Loans mature on August 1, 2018. The Company may prepay all, but not less than all, of the loaned amount upon 30 days’ advance notice to the Lenders, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3% of the outstanding balance, if the loan is prepaid within 24 months of the funding date, (ii) 2% of the outstanding balance, if the loan is prepaid between 24 and 36 months of the funding date and (iii) 1% of the outstanding balance, if the loan is prepaid thereafter (each, a “Prepayment Fee”). The expected remaining repayment of the $10.0 million Term A loan principal is $3,490,704 during 2018.

The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of its assets, other than its intellectual property. The Company has also agreed not to pledge or otherwise encumber its intellectual property assets, except that it may grant certain exclusive and non-exclusive licenses of its intellectual property as set forth in the Loan Agreement. In addition, the Company pledged all of its equity interests in Minerva Neurosciences Securities Corporation and 65% of its equity interests in Mind-NRG Sarl as security for its obligations under the Loan Agreement.

Upon the occurrence of certain events, including but not limited to the Company’s failure to satisfy its payment obligations under the Loan Agreement, the breach of certain of its other covenants under the Loan Agreement, or the occurrence of a material adverse change, the Lenders will have the right, among other remedies, to declare all principal and interest immediately due and payable, and will have the right to receive the final payment fee and, if the payment of principal and interest is due prior to maturity, the applicable Prepayment Fee. As of December 31, 2017, the Company was in compliance with all covenants set forth in the Loan Agreement.

Co-Development and License Agreement	12 Months Ended
Co-Development and License Agreement	Dec. 31, 2017
Co Development And License Agreement Disclosure [Abstract]
Co-Development and License Agreement	NOTE 6 — CO-DEVELOPMENT AND LICENSE AGREEMENT On February 13, 2014, the Company signed a co-development and license agreement (“the agreement”) with Janssen, which became effective upon completion of the Company’s initial public offering and the payment of a $22.0 million license fee. Under the agreement, Janssen, the licensor, granted the Company an exclusive license, with the right to sublicense, in the Minerva Territory, under (i) certain patent and patent applications to sell products containing any orexin 2 compound, controlled by the licensor and claimed in a licensor patent right as an active ingredient and (ii) seltorexant for any use in humans. In addition, upon regulatory approval in the Minerva Territory (and earlier if certain default events occur), the Company will have rights to manufacture seltorexant, also known as JNJ-42847922. The Company has granted to the licensor an exclusive license, with the right to sublicense, under all patent rights and know-how controlled by the Company related to seltorexant to sell seltorexant outside the Minerva Territory. In consideration of the licenses granted on July 7, 2014, the Company made a license fee payment of $22.0 million, which was included as a component of research and development expense in 2014. The original agreement contains certain provisions, which include the Company’s ability to opt-out of the agreement upon completion of certain milestones. If the Company elects to participate in the development program through to the potential commercial approval of seltorexant, the Company will pay a quarterly royalty percentage to the licensor in the high single digits on aggregate net sales for seltorexant products sold by the Company, its affiliates and sublicensees in the Minerva Territory. The licensor will pay a quarterly royalty percentage to the Company in the high single digits on aggregate net sales for seltorexant products sold by the licensor outside the Minerva Territory. In accordance with the development agreement, the Company will pay 40% of seltorexant development costs related to the joint development of any seltorexant products. The Company’s share of aggregate development costs shall not exceed (i) $5.0 million for the period beginning from the effective date of the license and ending following the completion of certain Phase 1b clinical trials and animal toxicology studies, and (ii) $24.0 million for the period beginning from the effective date of the license and ending following the completion of certain Phase 2 clinical trials. Janssen has a right to opt out at the end of certain development milestones, after which, Janssen will not have to fund further development of seltorexant and the Minerva Territory will be expanded to also include all of North America. The Company would then owe Janssen a reduced royalty in the mid-single digits for all sales in the Minerva Territory. Janssen may also terminate the agreement for the Company’s material breach or certain insolvency events, including if the Company is unable to fund its portion of the development costs. The Company accounts for the co-development and license agreement as a joint risk-sharing collaboration in accordance with ASC 808, Collaboration Arrangements. Payments between the Company and the licensor with respect to each party’s share of seltorexant development costs that have been incurred pursuant to the joint development plan are recorded within research and development expenses or general and administrative expenses, as applicable, in the accompanying consolidated statements of operations due to the joint risk-sharing nature of the activities. The Company has included zero and $2.5 million in accrued collaborative expenses, as of December 31, 2017 and December 31, 2016, respectively, related to this agreement. In the 12 months ended December 31, 2017 and 2016, the Company paid $2.5 million and zero, respectively, related to development activities under this agreement. On July 6, 2016, the Company and Janssen agreed that “Decision Point 2” had been reached as defined under the co-development agreement. As neither party has exercised their right to withdraw from the agreement, the Company has paid Janssen $3.5 million and have incurred direct expenses of $0.3 million related to development activities under the current phase of development. During the 12 months ended December 30, 2017 and 2016, the Company recorded an expense of $11.2 million and $3.5 million, respectively, for certain development activities in accordance with the terms of the co-development agreement. The company has included zero and $2.5 million in accrued collaborative expenses as of December 31, 2017 and December 31, 2016, respectively, related to this agreement. In June 2017, the Company entered into the Amendment. The effectiveness of the Amendment was contingent upon approval of its terms by the European Commission and the closing of the acquisition of Actelion by affiliates of Janssen. These conditions were subsequently met, and the agreement became effective on August 29, 2017. Under the amended agreement, Janssen has waived its right to royalties on seltorexant insomnia sales in the European Union, Switzerland, Liechtenstein, Iceland and Norway (the “Minerva Territory”). The Company retains all of its rights to seltorexant, including commercialization of the molecule for the treatment of insomnia and as an as adjunctive therapy for MDD, which include an exclusive license in the Minerva Territory, with royalties payable by the Company to Janssen on seltorexant MDD sales. Royalties on sales outside of the Minerva Territory are payable by Janssen to the Company. Janssen made an upfront payment to the Company of $30 million upon the effectiveness of the Amendment and agreed to make a $20 million payment at the start of a Phase 3 insomnia trial for seltorexant and a $20 million payment when 50% of the patients are enrolled in this trial. Janssen further agreed to waive the remaining payments due from the Company until completion of the Phase 2 development of seltorexant. The $30 million payment and $11.2 million in previously accrued collaborative expenses, which were forgiven upon the effective date of the agreement, will be earned and recognized as revenue as the services are performed from the commencement of Phase 3 development to the completion of the development activities using the proportional performance method. The $30 million payment along with the $11.2 million in previously accrued collaborative expenses have been included under Deferred Revenue on the Company’s balance sheet at December 31, 2017. In connection with the Amendment, the Company repurchased all of the approximately 3.9 million shares of its common stock previously owned by Johnson & Johnson Innovation-JJDC Inc. at a per share price of $0.0001, for an aggregate purchase price of approximately $389. As a result of the Amendment, the Company assumed strategic control for the clinical development of seltorexant in insomnia under the Phase 2 development program, but has no further financial obligations until the Phase 2b development milestone is complete, which is expected to occur in the second half of 2019. Upon completion of this development milestone, referred to as “Decision Point 4”, Minerva has the right to opt-out of the agreement and collect a royalty on worldwide sales of seltorexant in the single digits with no further obligations to Janssen. If the Company elects to continue past “Decision Point 4” into Phase 3, the Company would be obligated to fund the clinical trials related to insomnia, and receive $40 million in milestone payments from Janssen, and would also be responsible for 40% of all costs incurred in the Phase 3 MDD program. The Company determined that the license under the Amendment is not considered to be a separate deliverable as it contains no value without the development activities performed under the agreement. The participation in the joint steering committee under the Amendment is considered to be not separable from the development activities and therefore the two deliverables are combined into a single unit of account. The Company concluded that the milestone payments are solely dependent on future developments and therefore are considered non-substantive and will recognize such revenue in the periods in which the milestones are achieved. Similarly, the Company will recognize royalty revenues in the periods of the sale of the related products, provided that the reported sales are reliably measurable, collectability is reasonably assured and the Company has no further performance obligations.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Stockholders Equity Note [Abstract]
Stockholders' Equity	NOTE 7 — STOCKHOLDERS’ EQUITY Public Offering of Common Stock On July 5, 2017, the Company closed a public offering of its common stock, in which the Company issued and sold 5,750,000 shares of its common stock, including 750,000 shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares, at a public offering price of $7.75, for aggregate gross proceeds to the Company of $44.6 million. All of the shares issued and sold in this public offering were registered under the Securities Act pursuant to a registration statement on Form S-3 (File No. 333-205764) and a related prospectus and prospectus supplement, in each case filed with the Securities and Exchange Commission. The Company incurred $3.0 million in underwriting discounts and commissions and transaction costs, which will be included as a component of additional paid-in capital, resulting in net proceeds of approximately $41.6 million. On June 17, 2016, the Company closed a public offering of common stock, in which the Company issued and sold 6,052,631 shares of common stock at a public offering price of $9.50, for aggregate gross proceeds to the Company of $57.5 million. All of the shares issued and sold in this public offering were registered under the Securities Act pursuant to a registration statement on Form S-3 (File No. 333-205764) and a related prospectus and prospectus supplement, in each case filed with the Securities and Exchange Commission. The Company incurred $3.8 million in underwriting discounts and commissions and transaction costs, which have been included as a component of additional paid-in capital, resulting in net proceeds of $53.7 million. Share Repurchase In connection with the Janssen amendment (see Note 6), the Company repurchased all of the approximately 3.9 million shares of its common stock previously owned by Johnson & Johnson Innovation-JJDC Inc. at a per share price of $0.0001, for an aggregate purchase price of approximately $389. Warrant Exercises In January, February, June, December 2016, and March 2017, certain investors in the Company’s March 2015 private placement exercised their warrants at an exercise price of $5.772 per share and received an aggregate of 5,673,758 shares of the Company’s common stock. The Company received gross proceeds of approximately $32.7 million from the exercise of these warrants. Private Placement of Common Stock and Warrants On March 17, 2016, the Company entered into a common stock purchase agreement with a member of the Board of Directors, pursuant to which the Company, in a private placement, sold to the director an aggregate of 181,488 shares of the Company’s common stock, at a price per share of $5.51, for gross proceeds of approximately $1.0 million. On March 18, 2015, pursuant to a securities purchase agreement with certain accredited investors dated March 13, 2015, the Company sold in a private placement 6,281,661 shares of the Company’s common stock at a price per share of $4.81 and warrants to purchase up to an aggregate of 6,281,661 shares of common stock at a purchase price of $0.125 per warrant share, with an initial exercise price of $5.772 per share, resulting in gross proceeds of approximately $31.0 million. The Company incurred $2.5 million for placement agent fees and transaction costs which have been included as a component of additional paid-in capital, resulting in net proceeds of $28.5 million. The warrants expired on March 18, 2017, two years after the date on which they were initially issued. As of December 31, 2017, there were no remaining warrants outstanding under the Company’s March 2015 private placement. In connection with the private placement, the Company also entered into a registration rights agreement (the “Registration Rights Agreement”), dated March 13, 2015 with certain accredited investors. Pursuant to the terms of the Registration Rights Agreement, the Company was obligated to prepare and file with the SEC a registration statement to register for resale the 6,281,661 shares of its common stock issued in the private placement and the 6,281,661 shares of its common stock issuable upon exercise of the warrants on or prior to May 2, 2015. The Company filed a resale registration statement on Form S-1 (File No. 333-203737), which was declared effective by the SEC on May 11, 2015. The Company filed a post-effective amendment to the Form S-1 to convert the filing to a Form S-3 on July 2, 2015. If registration statements are not maintained effective, the Company could be subject to penalties of up to 10.0% of proceeds received in the private placement. Term Loan Warrants In connection with the Loan Agreement, the Company issued the Lenders warrants to purchase shares of its common stock upon its draw of each tranche of the Term Loans (see Note 5). The aggregate number of shares of common stock issuable upon exercise of the warrants is equal to 2.25% of the amount drawn of such tranche, divided by the average closing price per share of the Company’s common stock reported on the NASDAQ Global Market for the 10 consecutive trading days prior to the applicable draw. Upon the draw of the Term A Loans, the Company issued the Lenders warrants to purchase 40,790 shares of common stock at a per share exercise price of $5.516. The warrants are immediately exercisable upon issuance, and other than in connection with certain mergers or acquisitions, will expire on the ten-year anniversary of the date of issuance. The fair value of the warrants was estimated at $0.2 million using a Black-Scholes model and assuming: (i) expected volatility of 100.8%, (ii) risk free interest rate of 1.83%, (iii) an expected life of 10 years and (iv) no dividend payments. The fair value of the warrants was included as a discount to the Term A Loans and also as a component of additional paid-in capital and will be amortized to interest expense over the term of the loan. All such warrants were outstanding as of December 31, 2017.

Stock Award Plan and Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Award Plan and Stock-Based Compensation

NOTE 8 — STOCK AWARD PLAN AND STOCK-BASED COMPENSATION

In December 2013, the Company adopted the 2013 Equity Incentive Plan (as subsequently amended and restated, the “Plan”), which provides for the issuance of options, stock appreciation rights, stock awards and stock units. On January 1, 2017, in accordance with the terms of the Plan, the total shares authorized for issuance under the plan increased by 750,000 to 5,781,333. This increase represents the lesser of 750,000 shares or 4% of the total shares outstanding calculated as of the end of the most recent fiscal year. On December 11, 2017, the Company, issued inducement awards in the form of an option to purchase 775,000 shares of the Company’s common stock with an exercise price of $6.05 per share and restricted stock unit award to acquire 40,000 shares of the Company’s common stock, to Rick Russell in connection with his appointment as the Company’s President. These inducement awards are outside of, but subject to the terms generally consistent with, the Company’s 2013 Equity Incentive Plan, as amended, or the 2013 Plan, as a material inducement to Mr. Russell’s acceptance of employment with the Company in accordance with NASDAQ Listing Rule 5635(c)(4). The exercise price per share shall not be less than the fair value of the Company’s underlying common stock on the grant date and no option may have a term in excess of ten years. Stock option activity for employees and non-employees under the Plan for the year ended December 31, 2017 is as follows:

				Weighted-Average		Weighted-Average Remaining Contractual Term		Total Intrinsic Value
	Stock Options			Exercise Price		(years)		(in thousands)
Outstanding January 1, 2017		3,974,143		$	6.61		8.3

Granted		2,580,000		$	6.51
Exercised		(197,874	)	$	5.71
Forfeited		(223,619	)	$	8.06
Outstanding December 31, 2017		6,132,650		$	6.54		8.4	$	1,741
Exercisable December 31, 2017		2,563,008		$	6.25		7.1	$	961
Available for future grant		15,154

The weighted average grant-date fair value of stock options outstanding on December 31, 2017 was $4.98 per share. Total unrecognized compensation costs related to non-vested stock options at December 31, 2017 was approximately $16.6 million and is expected to be recognized within future operating results over a weighted-average period of 3.3 years. The total intrinsic value of the options exercised during the years ended December 31, 2017 and 2016 was approximately $0.7 million and $0.1 million, respectively. No options were exercised during the year ended December 31, 2015.

The expected term of the employee-related options was estimated using the “simplified” method as defined by the Securities and Exchange Commission’s Staff Accounting Bulletin No. 107, Share-Based Payment. The volatility assumption was determined by examining the historical volatilities for industry peer companies, as the Company does not have sufficient trading history for its common stock. The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the options. The dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has never paid dividends on its common stock and does not anticipate paying dividends on its common stock in the foreseeable future. Accordingly, the Company has assumed no dividend yield for purposes of estimating the fair value of the options

The Company uses the Black Scholes model to estimate the fair value of stock options granted. For stock options granted to employees during the years ended December 31, 2017, 2016, and 2015, the Company utilized the following assumptions:

	Years ended December 31,
	2017		2016		2015
Expected term (years)	5.5-6.25		5.5-6.25		5.5-6.25
Risk free interest rate	1.83-2.25%		1.17-2.22%		1.27-1.98%
Volatility	79-84%		78-79%		74-110%
Dividend yield	0%		0%		0%
Weighted average grant date fair value per share of common stock	$	4.50	$	8.47	$	3.83

Stock-Based Awards Granted to Non-employees-The Company from time to time grants options to purchase common stock to non-employees for services rendered and records expense ratably over the vesting period of each award. The Company estimates the fair value of the stock options using the Black-Scholes valuation model at each reporting date. The Company granted 480,000 stock options to non-employees and recorded stock-based compensation expense of $287,000 during the year ended December 31, 2017. The Company granted 60,000 stock options to non-employees and recorded stock-based compensation expense of $53,000 during the year ended December 31, 2016. There were no stock option grants made to non-employees made during the years ended December 31, 2015.

For stock options granted to non-employees, the Company utilized the following assumptions:

	Years ended December 31,
	2017		2016		2015
Expected term (years)	8.7-9.9		9.7			—
Risk free interest rate	2.37-2.40%		2.43%			—
Volatility	111-113%		104%			—
Dividend yield	0%		0%			—
Weighted average reporting date fair value per share of common stock	$	5.54	$	10.62		—

RSU activity under the Plan for the year ended December 31, 2017 is as follows:

				Weighted-Average
				Grant Date
	RSUs			Fair Value
Unvested January 1, 2017		219,600		$	13.45

Granted		40,000		$	6.05
Vested		(48,650	)	$	13.45
Forfeited		(25,000	)	$	13.45
Unvested December 31, 2017		185,950		$	11.86

RSUs awarded to employees generally vest one‑fourth per year over four years from the anniversary of the date of grant, provided the employee remains continuously employed with the Company. Shares of the Company’s stock are delivered to the employee upon vesting, subject to payment of applicable withholding taxes. The fair value of RSUs is equal to the closing price of the Company’s common stock on the date of grant. Total unrecognized compensation costs related to non-vested RSUs at December 31, 2017 was approximately $2.2 million and is expected to be recognized within future operating results over a weighted-average period of 3.1 years. The total fair value of shares vested during the year ended December 31, 2017, was approximately $0.3 million. No shares vested during the years ended December 31, 2016 or 2015.

The following table presents stock-based compensation expense included in the Company’s consolidated statements of operations:

	Years ended December 31,
	2017		2016		2015
Research and development	$	1,966,126	$	1,036,482	$	604,320
General and administrative		3,066,997		2,534,729		1,597,915
Total	$	5,033,123	$	3,571,211	$	2,202,235

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

NOTE 9 — INCOME TAXES

The provision for federal, foreign and state income taxes for the years ended December 31, 2017, 2016 and 2015 are as follows:

	Years ended December 31,
	2017			2016⁽¹⁾		2015⁽¹⁾
Current income tax provision (benefit)
Federal	$	—		$	—	$	—
Foreign		—			—		—
State		—			—		—
Deferred income tax provision (benefit)
Federal		(9,376,272	)		—		—
Foreign		—			—		—
State		—			—		—
Total income tax provision (benefit)	$	(9,376,272	)	$	—	$	—

(1)

There was no tax provision for income taxes for the year ended December 31, 2016 and 2015 due to losses.

Net deferred tax assets (liabilities) as of December 31, 2017 and 2016 consist of the following:

	December 31,			December 31,
	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	18,265,530		$	20,213,845
Research and development tax credits		145,115			145,115
Capitalized research and development costs		14,858,509			16,413,906
Stock-based compensation		4,180,651			4,741,558
Deferred start-up and license costs		6,532,419			10,258,431
Deferred Revenue		3,053,174			—
Other		129,082			—
Net deferred tax assets		47,164,480			51,772,855
Valuation allowance		(41,878,528	)		(51,772,855	)
Net deferred tax assets	$	5,285,952		$	—
Deferred tax liabilities:
In-process research and development	$	(9,343,440	)	$	(13,433,760	)
Net deferred tax liabilities		(4,057,488	)		(13,433,760	)

A reconciliation between the Company’s effective tax rate and the federal statutory rate for the years ended December 31, 2017, 2016 and 2015 are as follows:

	Years ended December 31,
	2017			2016			2015
Federal statutory rate		(34.00	%)		(34.00	%)		(34.00	%)
Permanent differences		0.66	%		0.76	%		0.53	%
State income taxes		0.00	%		(5.16	%)		(5.20	%)
Valuation allowance		56.33	%		38.40	%		38.67	%
Effective tax rate		22.99	%		0.00	%		0.00	%

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income, and tax planning strategies in making this assessment. Based upon the level of historical losses and the uncertainty of future taxable income over the periods which the Company will realize the benefits of its net deferred tax assets, management believes it is more likely than not that the Company will not realize the benefits on the balance of its net deferred tax asset and, accordingly, the Company has established a full valuation allowance on its net deferred tax assets. The valuation allowance decreased by approximately $9.9 million and increased by $11.9 million during the years ended December 31, 2017 and 2016.

As of December 31, 2017, the Company had approximately $64.8 million of Federal net operating losses that will begin to expire in 2027. As of December 31, 2017, the Company's wholly owned subsidiary had approximately $4.9 million of operating losses in Swizterland that will begin to expire in 2018. As of December 31, 2017, the Company had approximately $7.8 million of New Jersey and approximately $48.5 million of Massachusetts operating losses that will begin to expire in 2029 and 2033 respectively. As of December 31, 2017, the Company had approximately $0.2 million of federal research and development credits that will begin to expire in 2027. The Internal Revenue Code ("IRC") limits the amounts of net operating loss carryforwards that a company may use in any one year in the event of certain cumulative changes in ownership over a three-year period as described in Section 382 of the IRS. The Company has not performed a detailed analysis to determine whether an ownership change has occurred as of December 31, 2017.

This legislative change regarding the carryforward period of net operating losses impacts the Company’s indefinite lived deferred tax liabilities related to its IPR&D intangibles. Prior to the change in tax law, the Company’s net operating losses could not be used to offset deferred tax liabilities resulting from taxable temporary differences with an indefinite life. After the legislative change, federal net operating loss incurred after December 31, 2017 will have an indefinite life. As a result, the Company’s deductible temporary differences will reverse and create unlimited lived deferred tax assets which may be available to offset indefinite lived deferred tax liabilities. Accordingly, the Company has recognized a tax benefit for the period ending December 31, 2017 to reflect this reversal pattern.

The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s tax years are still open under statute from 2012 to the present.

As of December 31, 2017 and 2016, the Company had no liability recorded for unrecognized tax benefits. The Company classifies penalties and interest expense related to income tax liabilities as an income tax expense. There were no interest and penalties recognized in the statements of operations for the years ended December 31, 2017, 2016 and 2015, or accrued on the balance sheets as of December 31, 2017 and 2016.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 10 — COMMITMENTS AND CONTINGENCIES On October 2, 2017, the Company entered into an office sublease agreement (the “Sublease”) with Profitect, Inc. (the “Sublandlord”) to sublease approximately 5,923 rentable square feet of office space located at 1601 Trapelo Road, Waltham, MA 02451 (the “Premises”). The term of the Sublease began on November 1, 2017 and will expire on July 30, 2021, with a monthly rental rate starting at $14,807.50 and escalating to a maximum monthly rental rate of $16,288.25 in the final 12 months of the term. The Sublandlord has agreed to provide the Premises to the Company free of charge for the first two months of the term. From time to time, the Company may be subject to various legal proceedings and claims that arise in the ordinary course of the Company’s business activities. At this time, the Company is not aware of any such legal proceedings or claims. The Company is not aware of any claim or litigation, the outcome of which, if determined adversely to the Company, would have a material effect on the Company’s financial position or results of operations.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	NOTE 11 — RELATED PARTY TRANSACTIONS In January 2016, the Company entered into a services agreement with V-Watch SA (“V-Watch”), for approximately $105,000 for the use of V-Watch’s SomnoArt device for monitoring sleep in the roluperidone Phase IIb and MIN-117 Phase IIa trials. The Company’s Chief Executive Officer is the chairman of the board of directors of V-Watch. Funds affiliated with Index Ventures, a stockholder of the Company, hold greater than 10% of the outstanding capital stock of V-Watch. Also refer to Note 6 – Co-Development and License agreement and Note 7 – Stockholder’s Equity for additional related party transactions.

Quarterly Results (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results

NOTE 12 — QUARTERLY RESULTS (Unaudited)

	Three Months Ended
	March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(10,485	)		(9,746	)		(11,407	)		(9,532	)
Net income (loss)		(10,645	)		(9,780	)		(11,260	)		162
Loss per share, basic and diluted	$	(0.30	)	$	(0.27	)	$	(0.28	)	$	0.00

	Three Months Ended
	March 31, 2016			June 30, 2016			September 30, 2016			December 31, 2016
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(7,757	)		(4,965	)		(8,232	)		(9,237	)
Net loss		(8,004	)		(5,214	)		(8,423	)		(9,404	)
Loss per share, basic and diluted	$	(0.29	)	$	(0.18	)	$	(0.24	)	$	(0.27	)

	Three Months Ended
	March 31, 2015			June 30, 2015			September 30, 2015			December 31, 2015
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(5,878	)		(6,332	)		(5,705	)		(8,194	)
Net loss		(6,093	)		(6,610	)		(5,939	)		(8,439	)
Loss per share, basic and diluted	$	(0.31	)	$	(0.27	)	$	(0.24	)	$	(0.34	)

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	NOTE 13 — SUBSEQUENT EVENTS Stock Option Plan On January 1, 2018, in accordance with the terms of the Company’s 2013 Equity Incentive Plan, the total shares authorized for issuance under the plan increased by 750,000 to 6,531,333. This increase represents the lesser of 750,000 shares or 4% of the total shares outstanding calculated as of the end of the most recent fiscal year.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation

Basis of presentation

Consolidation

Significant Risks and Uncertainties

Significant risks and uncertainties

Use of Estimates

Use of estimates

Cash and Cash Equivalents

Cash and cash equivalents

Restricted Cash

Restricted cash

Marketable Securities

Marketable securities

	December 31, 2017
	Amortized		Aggregate		Unrealized		Unrealized		Net Carrying
	Cost		Fair Value		Gains		Losses		Value
Marketable securities current:
Corporate bonds/notes	$	43,528,246	$	43,438,463	$	89,783	$	—	$	43,528,246
Commercial paper		43,385,762		43,385,762		—		—		43,385,762
U.S. government agency securities		15,195,411		15,178,278		17,133		—		15,195,411
Marketable securities current total		102,109,419		102,002,503		106,916		—		102,109,419

Marketable securities non-current:
Corporate bonds/notes		5,022,982		4,998,870		24,112		—		5,022,982
Commercial paper		—		—		—		—		—
U.S. government agency securities		—		—		—		—		—
Marketable securities non-current total		5,022,982		4,998,870		24,112		—		5,022,982

Marketable securities total	$	107,132,401	$	107,001,373	$	131,028	$	—	$	107,132,401

Research and Development Costs

Research and development costs

In-Process Research and Development

In-process research and development

Stock-Based Compensation

Stock-based compensation

Foreign Currency Transactions

Foreign currency transactions

Loss Per Share

Loss per share

Income Taxes

Income taxes

Concentration of Credit Risk

Concentration of credit risk

Equipment

Long-Lived Assets

Long-lived assets

Goodwill

Fair Value of Financial Instruments

Fair value of financial instruments

Level 1 — Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	22,782,626	$	22,782,626	$	—	$	—
Marketable securities		107,132,401		—		107,132,401		—
Total fair value	$	129,915,027	$	22,782,626	$	107,132,401	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	15,260,809	$	15,260,809	$	—	$	—

Revenue Recognition

Revenue recognition

Deferred Revenue

Deferred revenue

The Company applies the revenue recognition guidance in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 605, Revenue Recognition. Using FASB ASC 605, Revenue that is unearned is deferred. Deferred revenue expected to be recognized as revenue more than one year subsequent to the balance sheet date is classified as long-term deferred revenue.

Segment Information

Segment information

Comprehensive Loss

Comprehensive loss

The Company had no items of comprehensive loss other than its net loss for each period presented.

Recent Accounting Pronouncements

Recent accounting pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) and are adopted by the Company as of the specified effective date.

Recently Adopted Accounting Pronouncements

Accounting Pronouncements Not Yet Adopted

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Amortized Cost Basis, Aggregate Fair Value, Net Unrealized (Gains)/Losses and Net Carrying Value of Investments in Held-to-maturity Securities

The following table provides the amortized cost basis, aggregate fair value, net unrealized (gains)/losses and the net carrying value of investments in held-to-maturity securities as of December 31, 2017:

	December 31, 2017
	Amortized		Aggregate		Unrealized		Unrealized		Net Carrying
	Cost		Fair Value		Gains		Losses		Value
Marketable securities current:
Corporate bonds/notes	$	43,528,246	$	43,438,463	$	89,783	$	—	$	43,528,246
Commercial paper		43,385,762		43,385,762		—		—		43,385,762
U.S. government agency securities		15,195,411		15,178,278		17,133		—		15,195,411
Marketable securities current total		102,109,419		102,002,503		106,916		—		102,109,419

Marketable securities non-current:
Corporate bonds/notes		5,022,982		4,998,870		24,112		—		5,022,982
Commercial paper		—		—		—		—		—
U.S. government agency securities		—		—		—		—		—
Marketable securities non-current total		5,022,982		4,998,870		24,112		—		5,022,982

Marketable securities total	$	107,132,401	$	107,001,373	$	131,028	$	—	$	107,132,401

Fair Value of Cash Equivalents and Marketable Securities Measured on Recurring Basis and Determined by Valuation Techniques

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	22,782,626	$	22,782,626	$	—	$	—
Marketable securities		107,132,401		—		107,132,401		—
Total fair value	$	129,915,027	$	22,782,626	$	107,132,401	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Cash equivalents	$	15,260,809	$	15,260,809	$	—	$	—

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

+ References + Details

Accrued Expenses and Other Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Payables And Accruals [Abstract]

Schedule of Accrued Expenses and Other Liabilities

Accrued expenses and other liabilities consist of the following:

	December 31, 2017		December 31, 2016
Research and development costs and other accrued expenses	$	1,162,441	$	574,290
Professional fees		251,000		192,000
Interest payable		20,508		49,523
Accrued bonus		5,899		—
	$	1,439,848	$	815,813

Net Loss Per Share of Common Stock (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Computation of Basic and Diluted Loss Per Share

The following table sets forth the computation of basic and diluted loss per share for common stockholders:

	Year Ended December 31,
	2017			2016			2015
Net loss	$	(31,523,207	)	$	(31,045,372	)	$	(27,081,632	)
Weighted average shares of common stock outstanding		37,937,191			31,514,154			23,412,181
Net loss per share of common stock – basic and diluted	$	(0.83	)	$	(0.99	)	$	(1.16	)

Securities Excluded from Calculation of Weighted Average Shares Outstanding as their Effect is Antidilutive

	December 31, 2017		December 31, 2016		December 31, 2015
Common stock options		6,132,650		3,974,143		3,388,698
Restricted stock units		185,950		219,600		—
Common stock warrants		40,790		2,269,766		6,322,451

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Summary of Outstanding Term A Loans and Debt Discount

The outstanding Term A Loans and debt discount are as follows:

	December 31, 2017
Term A Loans	$	3,490,704
Less: debt discount and financing costs		(15,550	)
Less: current portion		(3,962,664	)
Accrued portion of final payment		487,510
Long-term portion	$	—

Stock Award Plan and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Stock Option Activity for Employees and Non-Employees

Stock option activity for employees and non-employees under the Plan for the year ended December 31, 2017 is as follows:

				Weighted-Average		Weighted-Average Remaining Contractual Term		Total Intrinsic Value
	Stock Options			Exercise Price		(years)		(in thousands)
Outstanding January 1, 2017		3,974,143		$	6.61		8.3

Granted		2,580,000		$	6.51
Exercised		(197,874	)	$	5.71
Forfeited		(223,619	)	$	8.06
Outstanding December 31, 2017		6,132,650		$	6.54		8.4	$	1,741
Exercisable December 31, 2017		2,563,008		$	6.25		7.1	$	961
Available for future grant		15,154

Schedule of RSU Activity

RSU activity under the Plan for the year ended December 31, 2017 is as follows:

				Weighted-Average
				Grant Date
	RSUs			Fair Value
Unvested January 1, 2017		219,600		$	13.45

Granted		40,000		$	6.05
Vested		(48,650	)	$	13.45
Forfeited		(25,000	)	$	13.45
Unvested December 31, 2017		185,950		$	11.86

Schedule of Stock-Based Compensation Expense Included in the Company's Consolidated Statements of Operations

The following table presents stock-based compensation expense included in the Company’s consolidated statements of operations:

	Years ended December 31,
	2017		2016		2015
Research and development	$	1,966,126	$	1,036,482	$	604,320
General and administrative		3,066,997		2,534,729		1,597,915
Total	$	5,033,123	$	3,571,211	$	2,202,235

Employee Stock Option

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Assumptions Used in Black Scholes Model to Estimate Fair Value of Stock Options

	Years ended December 31,
	2017		2016		2015
Expected term (years)	5.5-6.25		5.5-6.25		5.5-6.25
Risk free interest rate	1.83-2.25%		1.17-2.22%		1.27-1.98%
Volatility	79-84%		78-79%		74-110%
Dividend yield	0%		0%		0%
Weighted average grant date fair value per share of common stock	$	4.50	$	8.47	$	3.83

Non-Employees Stock Options

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Assumptions Used in Black Scholes Model to Estimate Fair Value of Stock Options

For stock options granted to non-employees, the Company utilized the following assumptions:

	Years ended December 31,
	2017		2016		2015
Expected term (years)	8.7-9.9		9.7			—
Risk free interest rate	2.37-2.40%		2.43%			—
Volatility	111-113%		104%			—
Dividend yield	0%		0%			—
Weighted average reporting date fair value per share of common stock	$	5.54	$	10.62		—

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Provision for Federal, Foreign and State Income Taxes

The provision for federal, foreign and state income taxes for the years ended December 31, 2017, 2016 and 2015 are as follows:

	Years ended December 31,
	2017			2016⁽¹⁾		2015⁽¹⁾
Current income tax provision (benefit)
Federal	$	—		$	—	$	—
Foreign		—			—		—
State		—			—		—
Deferred income tax provision (benefit)
Federal		(9,376,272	)		—		—
Foreign		—			—		—
State		—			—		—
Total income tax provision (benefit)	$	(9,376,272	)	$	—	$	—

(1)

There was no tax provision for income taxes for the year ended December 31, 2016 and 2015 due to losses.

Schedule of Deferred Tax Assets and Liabilities

Net deferred tax assets (liabilities) as of December 31, 2017 and 2016 consist of the following:

	December 31,			December 31,
	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	18,265,530		$	20,213,845
Research and development tax credits		145,115			145,115
Capitalized research and development costs		14,858,509			16,413,906
Stock-based compensation		4,180,651			4,741,558
Deferred start-up and license costs		6,532,419			10,258,431
Deferred Revenue		3,053,174			—
Other		129,082			—
Net deferred tax assets		47,164,480			51,772,855
Valuation allowance		(41,878,528	)		(51,772,855	)
Net deferred tax assets	$	5,285,952		$	—
Deferred tax liabilities:
In-process research and development	$	(9,343,440	)	$	(13,433,760	)
Net deferred tax liabilities		(4,057,488	)		(13,433,760	)

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation between the Company’s effective tax rate and the federal statutory rate for the years ended December 31, 2017, 2016 and 2015 are as follows:

	Years ended December 31,
	2017			2016			2015
Federal statutory rate		(34.00	%)		(34.00	%)		(34.00	%)
Permanent differences		0.66	%		0.76	%		0.53	%
State income taxes		0.00	%		(5.16	%)		(5.20	%)
Valuation allowance		56.33	%		38.40	%		38.67	%
Effective tax rate		22.99	%		0.00	%		0.00	%

Quarterly Results (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

	Three Months Ended
	March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(10,485	)		(9,746	)		(11,407	)		(9,532	)
Net income (loss)		(10,645	)		(9,780	)		(11,260	)		162
Loss per share, basic and diluted	$	(0.30	)	$	(0.27	)	$	(0.28	)	$	0.00

	Three Months Ended
	March 31, 2016			June 30, 2016			September 30, 2016			December 31, 2016
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(7,757	)		(4,965	)		(8,232	)		(9,237	)
Net loss		(8,004	)		(5,214	)		(8,423	)		(9,404	)
Loss per share, basic and diluted	$	(0.29	)	$	(0.18	)	$	(0.24	)	$	(0.27	)

	Three Months Ended
	March 31, 2015			June 30, 2015			September 30, 2015			December 31, 2015
	(in thousands, except per share data)
Total revenues	$	—		$	—		$	—		$	—
Operating loss		(5,878	)		(6,332	)		(5,705	)		(8,194	)
Net loss		(6,093	)		(6,610	)		(5,939	)		(8,439	)
Loss per share, basic and diluted	$	(0.31	)	$	(0.27	)	$	(0.24	)	$	(0.34	)

NATURE OF OPERATIONS AND LIQUIDITY - Additional Information (Details)				12 Months Ended			15 Months Ended
	Aug. 29, 2017 USD ($)	Jul. 05, 2017 USD ($)	Jun. 17, 2016 USD ($)	Dec. 31, 2017 USD ($) License	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)
Nature Of Operations And Liquidity [Line Items]
Accumulated deficit				$ (164,381,441)	$ (132,858,234)
Net cash provided by operating activities				3,092,864	(25,687,674)	$ (24,269,419)
Cash, cash equivalents and marketable securities				133,200,000
Proceeds from exercise of common stock warrants				9,356,833	$ 23,392,098
Public Offering
Nature Of Operations And Liquidity [Line Items]
Net proceeds from issuance of common stock		$ 41,600,000	$ 53,700,000	41,600,000
Private Placement \| Warrants
Nature Of Operations And Liquidity [Line Items]
Proceeds from exercise of common stock warrants				9,400,000			$ 32,700,000
Amendment to Co-Development and License Agreement \| Janssen \| Seltorexant
Nature Of Operations And Liquidity [Line Items]
Upfront payment	$ 30,000,000			$ 30,000,000
Development-stage Proprietary Compounds
Nature Of Operations And Liquidity [Line Items]
Number of licenses acquired \| License				4

SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Restricted cash balances as collateral for corporate credit cards		$ 80,000	$ 80,000
Marketable securities, weighted average remaining maturity		4 months 24 days
Interest or penalties related to income taxes		$ 0	$ 0	$ 0
Corporate tax rate		34.00%	34.00%	34.00%
Income tax benefit due to federal rate change impact		$ 9,400,000
Equipment estimated useful life		3 years
Impairment of Long-Lived Assets		$ 0	$ 0
Impairment of goodwill		0	0
Revenues from product sales to date		$ 0
Number of operating segments \| Segment		1
Scenario Forecast
Significant Accounting Policies [Line Items]
Corporate tax rate	21.00%
Development-stage Proprietary Compounds
Significant Accounting Policies [Line Items]
Asset impairment charges		$ 0	$ 0

SIGNIFICANT ACCOUNTING POLICIES - Amortized Cost Basis, Aggregate Fair Value, Net Unrealized (Gains)/Losses and Net Carrying Value of Investments in Held-to-maturity Securities (Details)	Dec. 31, 2017 USD ($)
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	$ 107,132,401
Marketable securities, Aggregate Fair Value	107,001,373
Marketable securities, Unrealized Gains	131,028
Marketable securities, Net Carrying Value	107,132,401
Marketable Securities Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	102,109,419
Marketable securities, Aggregate Fair Value	102,002,503
Marketable securities, Unrealized Gains	106,916
Marketable securities, Net Carrying Value	102,109,419
Marketable Securities Non-Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	5,022,982
Marketable securities, Aggregate Fair Value	4,998,870
Marketable securities, Unrealized Gains	24,112
Marketable securities, Net Carrying Value	5,022,982
Corporate Bonds/Notes \| Marketable Securities Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	43,528,246
Marketable securities, Aggregate Fair Value	43,438,463
Marketable securities, Unrealized Gains	89,783
Marketable securities, Net Carrying Value	43,528,246
Corporate Bonds/Notes \| Marketable Securities Non-Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	5,022,982
Marketable securities, Aggregate Fair Value	4,998,870
Marketable securities, Unrealized Gains	24,112
Marketable securities, Net Carrying Value	5,022,982
Commercial Paper \| Marketable Securities Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	43,385,762
Marketable securities, Aggregate Fair Value	43,385,762
Marketable securities, Net Carrying Value	43,385,762
U.S. government Agency Securities \| Marketable Securities Current
Schedule Of Held To Maturity Securities [Line Items]
Marketable securities, Amortized Cost	15,195,411
Marketable securities, Aggregate Fair Value	15,178,278
Marketable securities, Unrealized Gains	17,133
Marketable securities, Net Carrying Value	$ 15,195,411

SIGNIFICANT ACCOUNTING POLICIES - Fair Value of Cash Equivalents and Marketable Securities Measured on Recurring Basis and Determined by Valuation Techniques (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	$ 129,915,027
Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	22,782,626	$ 15,260,809
Marketable Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	107,132,401
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	22,782,626
Level 1 \| Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	22,782,626	$ 15,260,809
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	107,132,401
Level 2 \| Marketable Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	$ 107,132,401

ACCRUED EXPENSES AND OTHER LIABILITIES - Accrued Expenses and Other Liabilities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Research and development costs and other accrued expenses	$ 1,162,441	$ 574,290
Professional fees	251,000	192,000
Interest payable	20,508	49,523
Accrued bonus	5,899
Accrued expenses and other liabilities	$ 1,439,848	$ 815,813

NET LOSS PER SHARE OF COMMON STOCK - Computation of Basic and Diluted Loss Per Share (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net loss	$ 162,000	$ (11,260,000)	$ (9,780,000)	$ (10,645,000)	$ (9,404,000)	$ (8,423,000)	$ (5,214,000)	$ (8,004,000)	$ (8,439,000)	$ (5,939,000)	$ (6,610,000)	$ (6,093,000)	$ (31,523,207)	$ (31,045,372)	$ (27,081,632)
Weighted average shares of common stock outstanding													37,937,191	31,514,154	23,412,181
Net loss per share of common stock – basic and diluted													$ (0.83)	$ (0.99)	$ (1.16)

NET LOSS PER SHARE OF COMMON STOCK - Securities Excluded from Calculation of Weighted Average Shares Outstanding as their Effect is Antidilutive (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Securities outstanding excluded from the calculation of weighted average shares outstanding	6,132,650	3,974,143	3,388,698
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Securities outstanding excluded from the calculation of weighted average shares outstanding	185,950	219,600
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Securities outstanding excluded from the calculation of weighted average shares outstanding	40,790	2,269,766	6,322,451

DEBT - Additional Information (Details)			12 Months Ended
DEBT - Additional Information (Details)	Aug. 31, 2015 USD ($)	Jan. 16, 2015 USD ($) Tranche	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)
Debt Instrument [Line Items]
Amortization of debt discount recorded as interest expense			$ 206,562	$ 347,771	$ 377,455
Loan and Security Agreement \| Term Loan
Debt Instrument [Line Items]
Aggregate principal amount		$ 15,000,000					$ 5,000,000
Number of tranches \| Tranche		2
Additional loan amount not borrowed						$ 5,000,000
Facility fee payment		$ 75,000
Final payment of term loan		5.10%
Amortization of debt discount recorded as interest expense			$ 200,000	300,000
Term loans maturity date			Aug. 01, 2018
Advance notice period to the lenders			30 days
Term loan prepayment fee terms			(i) 3% of the outstanding balance, if the loan is prepaid within 24 months of the funding date, (ii) 2% of the outstanding balance, if the loan is prepaid between 24 and 36 months of the funding date and (iii) 1% of the outstanding balance, if the loan is prepaid thereafter (each, a “Prepayment Fee”).
Loan and Security Agreement \| Term Loan \| Mind-NRG, Sarl
Debt Instrument [Line Items]
Percentage of equity interests			65.00%
Loan and Security Agreement \| Term Loan \| 24 months
Debt Instrument [Line Items]
Proportion of prepayment fees on outstanding balance			3.00%
Loan and Security Agreement \| Term Loan \| Between 24 and 36 months
Debt Instrument [Line Items]
Proportion of prepayment fees on outstanding balance			2.00%
Loan and Security Agreement \| Term Loan \| Prepaid Thereafter
Debt Instrument [Line Items]
Proportion of prepayment fees on outstanding balance			1.00%
Loan and Security Agreement \| Term Loan \| Term A Loans
Debt Instrument [Line Items]
Amount drew dawn during period		$ 10,000,000
Interest rate (as a percent)		7.05%
Minimum capital requirement	$ 30,000,000
Sale of equity securities	$ 20,000,000
Extended interest period for debt instrument			6 months
Reduced repayment period for debt instrument			6 months
Number of installments period			24 months
Interest expense			$ 600,000	$ 1,000,000
Expected remaining repayment during 2018			$ 3,490,704

DEBT - Summary of Outstanding Term A Loans and Debt Discount (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Less: current portion	$ (3,962,664)	$ (4,853,753)
Long-term portion		$ 3,841,062
Term Loan \| Term A Loans
Debt Instrument [Line Items]
Term A Loans	3,490,704
Less: debt discount and financing costs	(15,550)
Less: current portion	(3,962,664)
Accrued portion of final payment	$ 487,510

CO-DEVELOPMENT AND LICENSE AGREEMENT - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions					12 Months Ended
	Aug. 29, 2017	Jul. 06, 2016	Jul. 07, 2014	Feb. 13, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Co-development and license agreement
Research and development expense					$ 30,255,892	$ 20,439,994	$ 18,533,363
Deferred revenue					41,175,600
Aggregate purchase price					$ 389
Phase 3 Insomnia Trail
Co-development and license agreement
Percentage of milestone payment on aggregate product development cost					40.00%
Seltorexant \| Co-Development and License Agreement \| Phase 1b Clinical Trials \| Maximum
Co-development and license agreement
Share of aggregate development cost following completion of Phase 1b clinical trials and animal toxicology studies				$ 5,000,000
Seltorexant \| Co-Development and License Agreement \| Phase 2 Clinical Trials \| Maximum
Co-development and license agreement
Share of aggregate development cost following completion of Phase 1b clinical trials and animal toxicology studies				$ 24,000,000
Janssen \| Phase 3 Insomnia Trail
Co-development and license agreement
Milestone method payments					$ 40,000,000
Janssen \| Seltorexant \| Co-Development and License Agreement
Co-development and license agreement
Payment of license fee			$ 22,000,000
Percentage of development costs related to joint development of products				40.00%
Accrued collaborative expenses					0	2,500,000
Payment of development costs		$ 3,500,000			2,500,000	0
Direct expenses incurred		$ 300,000
Research and development expense					11,200,000	$ 3,500,000
Janssen \| Seltorexant \| Amendment to Co-Development and License Agreement
Co-development and license agreement
Accrued collaborative expenses	$ 11,200,000
Upfront payment	30,000,000				$ 30,000,000
Revenue recognition, milestone method, factors					The $30 million payment and $11.2 million in previously accrued collaborative expenses, which were forgiven upon the effective date of the agreement, will be earned and recognized as revenue as the services are performed from the commencement of Phase 3 development to the completion of the development activities using the proportional performance method.
Janssen \| Seltorexant \| Amendment to Co-Development and License Agreement \| Upfront Payment
Co-development and license agreement
Deferred revenue					$ 30,000,000
Janssen \| Seltorexant \| Amendment to Co-Development and License Agreement \| Previously Accrued Collaborative Expenses
Co-development and license agreement
Deferred revenue					$ 11,200,000
Janssen \| Seltorexant \| Amendment to Co-Development and License Agreement \| Phase 3 Insomnia Trail
Co-development and license agreement
Payment start of Phase	20,000,000
Payment upon enrollment of patients	$ 20,000,000
Percentage of patients to be enrolled	50.00%
Johnson & Johnson Innovation-JJDC Inc
Co-development and license agreement
Stock repurchased	3.9
Stock repurchased price per share	$ 0.0001
Aggregate purchase price	$ 389

STOCKHOLDERS' EQUITY - Public Offering of Common Stock - Additional Information (Details) - USD ($)			12 Months Ended
	Jul. 05, 2017	Jun. 17, 2016	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Proceeds from sale of common stock in public offering			$ 44,562,500	$ 57,499,995
Underwriting discounts and commissions and transaction costs			2,944,168	$ 3,832,004
Public Offering
Class Of Stock [Line Items]
Shares of common stock issued	5,750,000	6,052,631
Share price (in dollars per share)	$ 7.75	$ 9.50
Proceeds from sale of common stock in public offering	$ 44,600,000	$ 57,500,000
Underwriting discounts and commissions and transaction costs	3,000,000	3,800,000
Net proceeds from issuance of common stock	$ 41,600,000	$ 53,700,000	$ 41,600,000
Exercise of Underwriters
Class Of Stock [Line Items]
Shares of common stock issued	750,000

STOCKHOLDERS' EQUITY - Share Repurchase - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions		12 Months Ended
	Aug. 29, 2017	Dec. 31, 2017
Class Of Stock [Line Items]
Aggregate purchase price		$ 389
Johnson & Johnson Innovation-JJDC Inc
Class Of Stock [Line Items]
Stock repurchased	3.9
Stock repurchased price per share	$ 0.0001
Aggregate purchase price	$ 389

STOCKHOLDERS' EQUITY - Warrants Exercises - Additional Information (Details) - USD ($)	12 Months Ended		15 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Mar. 18, 2015
Class Of Warrant Or Right [Line Items]
Proceeds from exercise of warrants	$ 9,356,833	$ 23,392,098
Private Placement
Class Of Warrant Or Right [Line Items]
Common stock exercise price per share				$ 5.772
Private Placement \| Warrants
Class Of Warrant Or Right [Line Items]
Common stock exercise price per share			$ 5.772
Shares of common stock to purchase by warrant			5,673,758
Proceeds from exercise of warrants	$ 9,400,000		$ 32,700,000

STOCKHOLDERS' EQUITY - Private Placement of Common Stock and Warrants - Additional Information (Details) - USD ($)			12 Months Ended
	Mar. 17, 2016	Mar. 18, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2017
Class Of Stock [Line Items]
Gross proceeds from issuance of common stock and warrants	$ 1,000,000	$ 31,000,000		$ 999,999	$ 30,999,999
Private Placement
Class Of Stock [Line Items]
Sale of common stock, price per share		$ 4.81
Warrants price per share		0.125
Common stock exercise price per share		$ 5.772
Warrants expiration date		Mar. 18, 2017
Placement agent fees and transaction costs		$ 2,500,000			2,466,984
Net proceeds from issuance of common stock and warrants		$ 28,500,000		$ 999,999	$ 28,533,015
Registration rights agreement date			Mar. 13, 2015
Registration rights agreement term			Pursuant to the terms of the Registration Rights Agreement, the Company was obligated to prepare and file with the SEC a registration statement to register for resale the 6,281,661 shares of its common stock issued in the private placement and the 6,281,661 shares of its common stock issuable upon exercise of the warrants on or prior to May 2, 2015.
Penalty percentage for not meeting the registration agreement			10.00%
Common Stock \| Private Placement
Class Of Stock [Line Items]
Shares of common stock issued	181,488	6,281,661		181,488	6,281,661
Sale of common stock, price per share	$ 5.51
Shares of common stock to purchase by warrant		6,281,661
Net proceeds from issuance of common stock and warrants				$ 18	$ 628
Warrants \| Private Placement
Class Of Stock [Line Items]
Shares of common stock to purchase by warrant						5,673,758
Common stock exercise price per share						$ 5.772
Warrants outstanding			0

STOCKHOLDERS' EQUITY - Term Loan Warrants - Additional Information (Details) $ / shares in Units, $ in Millions	Jan. 16, 2015 USD ($) TradingDay $ / shares shares
Class Of Warrant Or Right [Line Items]
Fair value of warrants estimated \| $	$ 0.2
Warrant
Class Of Warrant Or Right [Line Items]
Expiration anniversary date of issuance	10 years
Expected stock price volatility (as a percent)	100.80%
Risk-free interest rate (as a percent)	1.83%
Expected life	10 years
Expected dividend	$ 0
Term Loan
Class Of Warrant Or Right [Line Items]
Aggregate number of shares of Common Stock issuable	2.25%
Consecutive trading days \| TradingDay	10
Term Loan \| Term A Loans
Class Of Warrant Or Right [Line Items]
Shares of common stock to purchase by warrant \| shares	40,790
Common stock exercise price per share	$ 5.516

STOCK AWARD PLAN AND STOCK-BASED COMPENSATION - Additional Information (Details) - USD ($)			12 Months Ended
	Dec. 11, 2017	Jan. 02, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2017
Stock Award Plan and Stock-Based Compensation
Fair value of common stock on grant date (in dollars per share)			$ 4.98
Total intrinsic value of the stock options exercised			$ 700,000	$ 100,000
Stock options exercised					0
Dividend yield (as a percent)			0.00%
Stock-based compensation expense			$ 5,033,123	$ 3,571,211	$ 2,202,235
Common Stock
Stock Award Plan and Stock-Based Compensation
Stock options exercised			197,874	16,055
Employee Stock Option
Stock Award Plan and Stock-Based Compensation
Fair value of common stock on grant date (in dollars per share)			$ 4.50	$ 8.47	$ 3.83
Total unrecognized compensation costs			$ 16,600,000
Weighted-average period over which unrecognized compensation costs is expected to be recognized			3 years 3 months 18 days
Dividend yield (as a percent)			0.00%	0.00%	0.00%
RSUs
Stock Award Plan and Stock-Based Compensation
Total unrecognized compensation costs			$ 2,200,000
Weighted-average period over which unrecognized compensation costs is expected to be recognized			3 years 1 month 6 days
Vesting rights percentage			25.00%
Vesting period			4 years
Description of vesting rights			RSUs awarded to employees generally vest one‑fourth per year over four years from the anniversary of the date of grant
Total fair value of shares vested			$ 300,000
Vested (in shares)			48,650	0	0
Non-Employees Stock Options
Stock Award Plan and Stock-Based Compensation
Dividend yield (as a percent)			0.00%	0.00%
Stock options granted			480,000	60,000	0
Stock-based compensation expense			$ 287,000	$ 53,000
2013 Equity Incentive Plan
Stock Award Plan and Stock-Based Compensation
Increase in number of shares authorized for issuance			750,000	750,000
Shares authorized for issuance under the plan						5,781,333
Additional shares authorized for issuance under the plan as percentage of total shares outstanding			4.00%
2013 Equity Incentive Plan \| Employee Stock Option \| Common Stock \| Rick Russell
Stock Award Plan and Stock-Based Compensation
Issuance of common stock and warrants, net of issuance costs (in shares)	775,000
Shares issued, price per share	$ 6.05
2013 Equity Incentive Plan \| RSUs \| Common Stock \| Rick Russell
Stock Award Plan and Stock-Based Compensation
Issuance of common stock and warrants, net of issuance costs (in shares)	40,000
Maximum \| 2013 Equity Incentive Plan \| Employee Stock Option
Stock Award Plan and Stock-Based Compensation
Term of share-based award		10 years

STOCK AWARD PLAN AND STOCK-BASED COMPENSATION - Stock Option Activity for Employees and Non-Employees (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options
Exercised (in shares)			0
Employees and Non-Employees Stock Option
Stock Options
Outstanding at the beginning of period (in shares)	3,974,143
Granted (in shares)	2,580,000
Exercised (in shares)	(197,874)
Forfeited (in shares)	(223,619)
Outstanding at the end of the period (in shares)	6,132,650	3,974,143
Exercisable at the end of the period (in shares)	2,563,008
Available for future grant (in shares)	15,154
Weighted-Average Exercise Price
Outstanding at the beginning of period (in dollars per share)	$ 6.61
Granted (in dollars per share)	6.51
Exercised (in dollars per share)	5.71
Forfeited (in dollars per share)	8.06
Outstanding at the end of the period (in dollars per share)	6.54	$ 6.61
Exercisable at the end of the period (in dollars per share)	$ 6.25
Weighted-Average Remaining Contractual Term Outstanding (years)	8 years 4 months 24 days	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term Exercisable (years)	7 years 1 month 6 days
Total Intrinsic Value Outstanding	$ 1,741
Total Intrinsic Value Exercisable	$ 961

STOCK AWARD PLAN AND STOCK-BASED COMPENSATION - Summary of Assumptions Used in Black Scholes Model to Estimate Fair Value of Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Award Plan and Stock-Based Compensation
Dividend yield	0.00%
Weighted average grant date fair value per share of common stock	$ 4.98
Employee Stock Option
Stock Award Plan and Stock-Based Compensation
Dividend yield	0.00%	0.00%	0.00%
Weighted average grant date fair value per share of common stock	$ 4.50	$ 8.47	$ 3.83
Employee Stock Option \| Minimum
Stock Award Plan and Stock-Based Compensation
Expected term (years)	5 years 6 months	5 years 6 months	5 years 6 months
Risk free interest rate	1.83%	1.17%	1.27%
Volatility	79.00%	78.00%	74.00%
Employee Stock Option \| Maximum
Stock Award Plan and Stock-Based Compensation
Expected term (years)	6 years 3 months	6 years 3 months	6 years 3 months
Risk free interest rate	2.25%	2.22%	1.98%
Volatility	84.00%	79.00%	110.00%
Non-Employees Stock Options
Stock Award Plan and Stock-Based Compensation
Expected term (years)		9 years 8 months 12 days
Risk free interest rate		2.43%
Volatility		104.00%
Dividend yield	0.00%	0.00%
Weighted average reporting date fair value per share of common stock	$ 5.54	$ 10.62
Non-Employees Stock Options \| Minimum
Stock Award Plan and Stock-Based Compensation
Expected term (years)	8 years 8 months 12 days
Risk free interest rate	2.37%
Volatility	111.00%
Non-Employees Stock Options \| Maximum
Stock Award Plan and Stock-Based Compensation
Expected term (years)	9 years 10 months 24 days
Risk free interest rate	2.40%
Volatility	113.00%

STOCK AWARD PLAN AND STOCK-BASED COMPENSATION - Schedule of RSU Activity (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options
Unvested at the beginning of the period (in shares)	219,600
Granted (in shares)	40,000
Vested (in shares)	(48,650)	0	0
Forfeited (in shares)	(25,000)
Unvested at the end of the period (in shares)	185,950	219,600
Weighted-Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share)	$ 13.45
Granted (in dollars per share)	6.05
Vested (in dollars per share)	13.45
Forfeited (in dollars per share)	13.45
Unvested at the end of the period (in dollars per share)	$ 11.86	$ 13.45

STOCK AWARD PLAN AND STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense Included in the Company's Consolidated Statements of Operations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 5,033,123	$ 3,571,211	$ 2,202,235
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	1,966,126	1,036,482	604,320
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 3,066,997	$ 2,534,729	$ 1,597,915

INCOME TAXES - Schedule of Provision for Federal, Foreign and State Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax provision (benefit)
Federal	$ (9,376,272)
Total income tax provision (benefit)	$ (9,376,272)	$ 0	$ 0

INCOME TAXES - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Provision for income taxes		$ (9,376,272)	$ 0	$ 0
Increase (decrease) in valuation allowance on net deferred tax assets		$ (9,900,000)	$ 11,900,000
Corporate tax rate		34.00%	34.00%	34.00%
Income tax benefit		$ 9,376,272	$ 0	$ 0
Unrecognized tax benefits, liability		0	0
Interest and penalties recognized		0	0	$ 0
Interest and penalties accrued		0	$ 0
Scenario Forecast
Operating Loss Carryforwards [Line Items]
Corporate tax rate	21.00%
Federal
Operating Loss Carryforwards [Line Items]
Net operating losses		$ 64,800,000
Operating losses, year begin to expire		2027
Federal \| Federal research and development
Operating Loss Carryforwards [Line Items]
Federal research and development credits		$ 200,000
Federal research and development credits expiration year		2027
Switzerland
Operating Loss Carryforwards [Line Items]
Net operating losses		$ 4,900,000
Operating losses, year begin to expire		2018
New jersey
Operating Loss Carryforwards [Line Items]
Net operating losses		$ 7,800,000
Operating losses, year begin to expire		2029
Massachusetts
Operating Loss Carryforwards [Line Items]
Net operating losses		$ 48,500,000
Operating losses, year begin to expire		2033

INCOME TAXES - Net Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 18,265,530	$ 20,213,845
Research and development tax credits	145,115	145,115
Capitalized research and development costs	14,858,509	16,413,906
Stock-based compensation	4,180,651	4,741,558
Deferred start-up and license costs	6,532,419	10,258,431
Deferred Revenue	3,053,174
Other	129,082
Net deferred tax assets	47,164,480	51,772,855
Valuation allowance	(41,878,528)	(51,772,855)
Net deferred tax assets	5,285,952
Deferred tax liabilities:
In-process research and development	(9,343,440)	(13,433,760)
Net deferred tax liabilities	$ (4,057,488)	$ (13,433,760)

INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory rate	(34.00%)	(34.00%)	(34.00%)
Permanent differences	0.66%	0.76%	0.53%
State income taxes	0.00%	(5.16%)	(5.20%)
Valuation allowance	56.33%	38.40%	38.67%
Effective tax rate	22.99%	0.00%	0.00%

COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - Office Sublease Agreement - Profitect, Inc	Oct. 02, 2017 USD ($) ft²
Loss Contingencies [Line Items]
Sublease rentable square feet \| ft²	5,923
Lease description	The term of the Sublease began on November 1, 2017 and will expire on July 30, 2021, with a monthly rental rate starting at $14,807.50 and escalating to a maximum monthly rental rate of $16,288.25 in the final 12 months of the term. The Sublandlord has agreed to provide the Premises to the Company free of charge for the first two months of the term.
Lease commencement date	Nov. 01, 2017
Sublease expire date	Jul. 30, 2021
Minimum
Loss Contingencies [Line Items]
Monthly rental rate	$ 14,807.50
Maximum
Loss Contingencies [Line Items]
Monthly rental rate	$ 16,288.25

RELATED PARTY TRANSACTIONS - Additional Information (Details) - V - Watch SA	1 Months Ended
	Jan. 31, 2016 USD ($)
Related Party Transaction [Line Items]
Services agreement	$ 105,000
Minimum
Related Party Transaction [Line Items]
Percentage of outstanding capital stock	10.00%

QUARTERLY RESULTS (Unaudited) - Schedule of Quarterly Financial Information (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Operating loss	$ (9,532,000)	$ (11,407,000)	$ (9,746,000)	$ (10,485,000)	$ (9,237,000)	$ (8,232,000)	$ (4,965,000)	$ (7,757,000)	$ (8,194,000)	$ (5,705,000)	$ (6,332,000)	$ (5,878,000)	$ (41,170,161)	$ (30,190,696)	$ (26,109,619)
Net income (loss)	$ 162,000	$ (11,260,000)	$ (9,780,000)	$ (10,645,000)	$ (9,404,000)	$ (8,423,000)	$ (5,214,000)	$ (8,004,000)	$ (8,439,000)	$ (5,939,000)	$ (6,610,000)	$ (6,093,000)	$ (31,523,207)	$ (31,045,372)	$ (27,081,632)
Loss per share, basic and diluted	$ 0.00	$ (0.28)	$ (0.27)	$ (0.30)	$ (0.27)	$ (0.24)	$ (0.18)	$ (0.29)	$ (0.34)	$ (0.24)	$ (0.27)	$ (0.31)

SUBSEQUENT EVENTS - Additional Information (Details) - 2013 Equity Incentive Plan - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017
Subsequent Event [Line Items]
Shares authorized for issuance				5,781,333
Increase in number of shares authorized for issuance	750,000	750,000
Subsequent Event
Subsequent Event [Line Items]
Shares authorized for issuance			6,531,333
Increase in shares authorized for issuance as percentage of shares outstanding			4.00%