ACADIA Pharmaceuticals (ACAD) 10-K 26 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Jan. 30, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	ACAD
Entity Registrant Name	ACADIA PHARMACEUTICALS INC
Entity Central Index Key	1070494
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		100,171,719
Entity Public Float			$1.40

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Cash and cash equivalents	$61,854	$11,707
Investment securities, available-for-sale	260,632	174,083
Interest and other receivables	964	750
Prepaid expenses and other current assets	1,168	1,820
Total current assets	324,618	188,360
Property and equipment, net	553	579
Other assets	287	179
Total assets	325,458	189,118
Liabilities and stockholders' equity
Accounts payable	2,016	372
Accrued expenses	13,818	6,552
Deferred revenue		55
Total current liabilities	15,834	6,979
Long-term liabilities	135	8
Total liabilities	15,969	6,987
Commitments and contingencies (Note 10)
Stockholders' equity
Preferred stock, $0.0001 par value; 5,000,000 shares authorized at December 31, 2014 and 2013; no shares issued and outstanding at December 31, 2014 and 2013
Common stock, $0.0001 par value; 150,000,000 shares authorized at December 31, 2014 and 2013; 100,047,331 shares and 91,102,618 shares issued and outstanding at December 31, 2014 and 2013, respectively	10	9
Additional paid-in capital	807,631	587,742
Accumulated deficit	-498,143	-405,668
Accumulated other comprehensive (loss) income	-9	48
Total stockholders' equity	309,489	182,131
Total liabilities and stockholders' equity	$325,458	$189,118

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	100,047,331	91,102,618
Common stock, shares outstanding	100,047,331	91,102,618

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues
Collaborative revenues	$120		$1,145		$4,907
Operating expenses
Research and development (includes stock-based compensation expense of $5,191, $2,208, and $680, respectively)	60,602		26,722		18,794
General and administrative (includes stock-based compensation expense of $10,848, $3,503, and $1,250, respectively)	32,748		12,720		6,999
Total operating expenses	93,350		39,442		25,793
Loss from operations	-93,230		-38,297		-20,886
Interest income, net	755		349		37
Net loss	($92,475)		($37,948)		($20,849)
Net loss per common share, basic and diluted	($0.95)	[1]	($0.44)	[1]	($0.38)
Weighted average common shares outstanding, basic and diluted	97,248		85,715		55,116
[1]	Net loss per common share, basic and diluted, are computed independently for each quarter and the full year based upon respective average shares outstanding. Therefore, the sum of the quarterly net loss per common share amounts may not equal the annual amounts reported.

Consolidated_Statements_of_Ope1

Consolidated Statements of Operations (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation	$16,039	$5,711	$1,930
Research and development
Stock-based compensation	5,191	2,208	680
General and administrative
Stock-based compensation	$10,848	$3,503	$1,250

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net loss	($92,475)	($37,948)	($20,849)
Other comprehensive loss:
Unrealized gain (loss) on investment securities	-60	45	-4
Foreign currency translation adjustments	3	-1	-1
Comprehensive loss	($92,532)	($37,904)	($20,854)

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net loss	($92,475)	($37,948)	($20,849)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	16,039	5,711	1,930
Amortization of premiums and accretion of discounts on investment securities, available for sale	484	1,528	-133
Gain on disposal of assets		-10	-252
Depreciation and amortization	206	79	109
Changes in operating assets and liabilities:
Interest and other receivables	-214	-505	279
Prepaid expenses and other current assets	652	-1,484	41
Other assets	-108	-179	14
Accounts payable	1,644	-1,003	-585
Accrued expenses	7,266	2,413	635
Deferred revenue	-55	-379	-2,822
Long-term liabilities	127	8
Net cash used in operating activities	-66,434	-31,769	-21,633
Cash flows from investing activities
Purchases of investment securities	-335,361	-211,585	-56,728
Maturities of investment securities	248,268	86,087	30,948
Purchases of property and equipment	-180	-618
Proceeds from sales of property and equipment		12	252
Net cash used in investing activities	-87,273	-126,104	-25,528
Cash flows from financing activities
Proceeds from issuances of equity securities, net of issuance costs	203,851	111,682	98,204
Repayments of long-term debt			-32
Net cash provided by financing activities	203,851	111,682	98,172
Effect of exchange rate changes on cash	3	-1	-1
Net increase (decrease) in cash and cash equivalents	50,147	-46,192	51,010
Cash and cash equivalents
Beginning of year	11,707	57,899	6,889
End of year	$61,854	$11,707	$57,899

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
In Thousands, except Share data
Beginning balance at Dec. 31, 2011	$23,362	$5	$370,219	($346,871)	$9
Beginning balance (in shares) at Dec. 31, 2011		52,898,659
Issuance of common stock and warrants, net of issuance costs (in shares)		19,000,000
Issuance of common stock and warrants, net of issuance costs	80,538	2	80,536
Issuance of common stock from exercise of stock options (in shares)		293,595
Issuance of common stock from exercise of stock options	453		453
Issuance of common stock pursuant to employee stock purchase plan (in shares)	205,862	205,862
Issuance of common stock pursuant to employee stock purchase plan	123		123
Issuance of common stock from exercise of warrants on a net issuance basis (in shares)	874,719	936,100
Issuance of common stock from exercise of warrants on a net issuance basis	0	0	0	0	0
Issuance of common stock under ATM Agreement, net of issuance costs (in shares)		5,347,137
Issuance of common stock under ATM Agreement, net of issuance costs	17,090	1	17,089
Reclassification to redeemable common stock (in shares)		-5,347,137
Reclassification to redeemable common stock	-17,658	-1	-17,657
Net loss	-20,849			-20,849
Stock-based compensation	1,930		1,930
Other comprehensive income (loss)	-5				-5
Ending balance at Dec. 31, 2012	84,984	7	452,693	-367,720	4
Ending balance (in shares) at Dec. 31, 2012		73,334,216
Issuance of common stock in public offering, net of issuance costs (in shares)		9,200,000
Issuance of common stock in public offering, net of issuance costs	107,883	1	107,882
Issuance of common stock from exercise of stock options (in shares)		1,455,406
Issuance of common stock from exercise of stock options	3,441		3,441
Issuance of common stock pursuant to employee stock purchase plan (in shares)	122,853	122,853
Issuance of common stock pursuant to employee stock purchase plan	358		358
Issuance of common stock from exercise of warrants on a net issuance basis (in shares)	1,643,006	1,643,006
Issuance of common stock from exercise of warrants on a net issuance basis	0	0	0	0	0
Reclassification from redeemable common stock (in shares)		5,347,137
Reclassification from redeemable common stock	17,658	1	17,657
Net loss	-37,948			-37,948
Stock-based compensation	5,711		5,711
Other comprehensive income (loss)	44				44
Ending balance at Dec. 31, 2013	182,131	9	587,742	-405,668	48
Ending balance (in shares) at Dec. 31, 2013		91,102,618
Issuance of common stock in public offering, net of issuance costs (in shares)		7,360,000
Issuance of common stock in public offering, net of issuance costs	196,779	1	196,778
Issuance of common stock from exercise of stock options (in shares)	1,486,802	1,486,802
Issuance of common stock from exercise of stock options	6,408		6,408
Issuance of common stock pursuant to employee stock purchase plan (in shares)	97,911	97,911
Issuance of common stock pursuant to employee stock purchase plan	664		664
Net loss	-92,475			-92,475
Stock-based compensation	16,039		16,039
Other comprehensive income (loss)	-57				-57
Ending balance at Dec. 31, 2014	$309,489	$10	$807,631	($498,143)	($9)
Ending balance (in shares) at Dec. 31, 2014		100,047,331

Organization_and_Nature_of_Ope

Organization and Nature of Operations	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Organization and Nature of Operations	1. Organization and Nature of Operations
	ACADIA Pharmaceuticals Inc. (the “Company”) was originally incorporated in Vermont in 1993 as Receptor Technologies, Inc. The Company reincorporated in Delaware in 1997 and its operations are based in San Diego, California. The Company is focused on the development and commercialization of innovative small molecule drugs that address unmet medical needs in neurological and related central nervous system disorders.
	The Company has incurred substantial operating losses since its inception due in large part to expenditures for its research and development activities. As of December 31, 2014, the Company had an accumulated deficit of $498.1 million. The Company expects to continue to incur operating losses for at least the next several years as it pursues the development and commercialization of its product candidates.
	The Company may require significant additional financing in the future to fund its operations. Future capital requirements will depend on many factors, including the progress in, the outcome of and the costs of the Company’s development and regulatory activities, including the ability of the Company to obtain regulatory approval for its products, costs associated with establishing necessary sales and marketing capabilities, the amount of product sales, if any, the scope, prioritization and number of its research and development programs, the ability of its collaborators and the Company to reach milestones and other events or developments under its collaboration and license agreements, and the ability of the Company to enter into new, and to maintain existing, collaboration and license agreements. Unless and until the Company can generate significant cash from operations, it expects to fund its operations through its existing cash, cash equivalents and investment securities, payments from existing and potential future collaborations, proceeds from public or private sales of its equity securities, debt financing, grant funding, or by licensing all or a portion of its product candidates or technology. The Company cannot be certain that adequate additional funding will be available on acceptable terms, or at all. Conditions in the financial markets and other factors could have a material adverse effect on the Company’s ability to access sufficient funding on acceptable terms, or at all. If the Company needs but cannot raise adequate additional capital, it will be required to delay, reduce the scope of, or eliminate one or more of its research or development programs or its commercialization efforts. In such circumstances, the Company may also be required to relinquish greater, or even all, rights to product candidates at earlier stages of development or commercialization or on less favorable terms than it would otherwise choose.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies
	Significant accounting policies followed in the preparation of these financial statements are as follows:
	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries located in Europe. All intercompany accounts and transactions have been eliminated in consolidation.
	Use of Estimates
	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with an initial maturity date at the date of purchase of three months or less to be cash equivalents.
	Investment Securities
	The Company has classified all of its investment securities as available-for-sale and, accordingly, carries these investments at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity. The cost of investment securities classified as available-for-sale is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. Realized gains and losses, if any, are also included in interest income. The cost of securities sold is based on the specific identification method.
	Fair Value of Financial Instruments
	The carrying values of the Company’s financial instruments, consisting of cash and cash equivalents, interest and other receivables, and accounts payable and accrued expenses, approximate fair value due to the relative short-term nature of these instruments.
	As disclosed in Note 4, the Company classifies its cash equivalents and available-for-sale investment securities within the fair value hierarchy as defined by authoritative guidance:
	Level 1 Inputs		—		Quoted prices for identical instruments in active markets.
	Level 2 Inputs		—		Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable.
	Level 3 Inputs		—		Valuation derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.
	Property and Equipment
	Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight line method. Leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the lease by use of the straight line method. Construction-in-process reflects amounts incurred for property, equipment or improvements that have not been placed in service. Maintenance and repair costs are expensed as incurred. When assets are retired or sold, the assets and accumulated depreciation are removed from the respective accounts and any gain or loss is recognized.
	Estimated useful lives by major asset category are as follows:
		Useful Lives
	Machinery and equipment		5 to 7 years
	Computers and software		3 years
	Furniture and fixtures		10 years
	Impairment of Long-Lived Assets
	The Company reviews its long lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. No such impairment losses have been recorded by the Company.
	Revenues
	The Company recognizes revenues in accordance with authoritative guidance established by GAAP. The Company’s revenues are primarily related to its collaboration agreements, which may provide for various types of payments, including upfront payments, funding of research and development, milestone payments, and licensing fees. The Company’s collaboration agreements also include potential payments for product royalties; however, the Company has not received any product royalties to date.
	The Company considers a variety of factors in determining the appropriate method of accounting under its collaboration agreements, including whether the various elements can be separated and accounted for individually as separate units of accounting. Where there are multiple deliverables identified within a collaboration agreement that are combined into a single unit of accounting, revenues are deferred and recognized over the expected period of performance. The specific methodology for the recognition of the revenue is determined on a case-by-case basis according to the facts and circumstances of the applicable agreement.
	Upfront, non-refundable payments that do not have stand-alone value are recorded as deferred revenue once received and recognized as revenues over the expected period of performance. Revenues from non-refundable license fees are recognized upon receipt of the payment if the license has stand-alone value, the Company does not have ongoing involvement or obligations, and the Company can determine the best estimate of the selling price for any undelivered items. When non-refundable license fees do not meet all of these criteria, the license revenues are recognized over the expected period of performance. Non-refundable payments for research funding are generally recognized as revenues over the period the related research activities are performed. Payments for reimbursement of external development costs are generally recognized as revenues using a contingency-adjusted performance model over the expected period of performance. Payments received from grants are recognized as revenues as the related research and development is performed and when collectability has been reasonably assured.
	The Company evaluates milestone payments on an individual basis and recognizes revenues from non-refundable milestone payments when the earnings process is complete and collectability is reasonably assured. Non-refundable milestone payments related to arrangements under which the Company has continuing performance obligations are recognized as revenues upon achievement of the associated milestone, provided that (i) the milestone event is substantive and its achievability was not reasonably assured at the inception of the agreement and (ii) the amount of the milestone payment is reasonable in relation to the effort expended or the risk associated with the milestone event. Where separate milestone payments do not meet these criteria, the Company recognizes revenue using a contingency-adjusted performance model over the expected period of performance.
	Research and Development Expenses
	Research and development expenses are charged to operations as incurred. Research and development expenses include, among other things, costs associated with services provided by contract organizations for preclinical development, manufacturing of product candidates, and clinical trials. The Company accrues for costs incurred as the services are being provided by monitoring the status of the trial or services provided and the invoices received from its external service providers. In the case of clinical trials, a portion of the estimated cost normally relates to the projected cost to treat a patient in the trials, and this cost is recognized based on the number of patients enrolled in the trial. Other indirect costs are generally recognized on a straight-line basis over the estimated period of the study. As actual costs become known, the Company adjusts its accruals. Certain research and development programs are funded under agreements with collaboration partners, and the Company’s costs related to these activities are included in research and development expenses.
	Concentrations of Risk
	Financial instruments, which potentially subject the Company to concentrations of credit risk, principally consist of cash, cash equivalents, and investment securities. The Company currently invests its excess cash primarily in a money market fund, U.S. Treasury notes, and high quality, marketable debt instruments of corporations, financial institutions and government sponsored enterprises in accordance with the Company’s investment policy. The Company’s investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. All investment securities have a credit rating of at least A3/A- or better, or P-1/A-1 or better, as determined by Moody’s Investors Service or Standard & Poor’s.
	During the years ended December 31, 2014, 2013 and 2012, revenues from the Company’s agreements with certain collaborative partners exceeded 10 percent of its total revenues. During the year ended December 31, 2014, revenues from Fast Forward, LLC and Allergan, Inc. comprised 59 percent and 33 percent of total revenues, respectively. During the year ended December 31, 2013, revenues from Allergan, the National Institutes of Health, and The Michael J. Fox Foundation comprised 50 percent, 19 percent, and 15 percent of total revenues, respectively. During the year ended December 31, 2012, revenues from Allergan and Meiji Seika Pharma Co., Ltd. comprised 23 percent and 66 percent of total revenues, respectively.
	The Company does not currently have any of its own manufacturing facilities, and therefore relies on third-party manufacturers to produce its product candidates for clinical trials. Although there are potential sources of supply other than the Company’s existing suppliers, any new supplier would be required to qualify under applicable regulatory requirements.
	Stock-Based Compensation
	The fair value of each employee stock option and each employee stock purchase right granted is estimated on the grant date under the fair value method using the Black-Scholes valuation model. The estimated fair value of each stock option and purchase right, including the effect of estimated forfeitures, is then expensed over the requisite service period, which is generally the vesting period. The following assumptions were used during these periods:
		Years Ended December 31,
		2014			2013			2012
	Stock Options:
	Expected volatility		93	%		94	%		98-99	%
	Risk-free interest rate		2-Jan	%		2-Jan	%		1	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		5.7			6			5.8-6.0
		Years Ended December 31,
		2014			2013			2012
	Employee Stock Purchase Plan:
	Expected volatility		44-95	%		69-118	%		69-137	%
	Risk-free interest rate		0.1-0.5	%		0.1-0.3	%		0.1-0.3	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		0.5-2.0			0.5-2.0			0.5-2.0
	Expected Volatility. The Company considers its historical volatility and implied volatility when determining the expected volatility.
	Risk-Free Interest Rate. The Company determines its risk-free interest rate assumption based on the U.S. Treasury yield for obligations with contractual terms similar to the expected term of the stock option or purchase right being valued.
	Expected Dividend Yield. The Company has never paid any dividends and currently has no plans to do so.
	Expected Life of Options. The Company considers, among other factors, its historical exercise experience to date as well as the mean time remaining to full vesting of all outstanding options and the mean time remaining to the end of the contractual term of all outstanding options.
	Income Taxes
	Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. A deferred income tax asset or liability is computed for the expected future impact of differences between the financial reporting and income tax bases of assets and liabilities and for the expected future tax benefit to be derived from tax credits and loss carryforwards. Deferred income tax expense or benefit represents the net change during the year in the deferred income tax asset or liability. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized.
	Net Loss Per Share
	Net loss per share is presented as basic and diluted net loss per share. Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss by the weighted average number of common shares and common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, stock options and warrants are considered to be common stock equivalents but are not included in the calculations of diluted net loss per share for the periods presented as their effect would be antidilutive.
	Shares used in calculating basic and diluted net loss per common share exclude the following potential common shares as their effect is antidilutive (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Antidilutive options to purchase common stock		7,773			7,245			6,868
Antidilutive warrants to purchase common stock		1,966			3,116			4,388
		9,739			10,361			11,256
Segment Reporting
Management has determined that the Company operates in one business segment. All revenues for the years ended December 31, 2014, 2013 and 2012 were generated in the United States.
Recently Issued Accounting Standards
In May 2014, the Financial Accounting Standards Board issued authoritative accounting guidance related to revenue from contracts with customers. This guidance is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This guidance is effective for annual reporting periods beginning after December 15, 2016 and early adoption is not permitted. The Company will adopt this guidance on January 1, 2017. Companies may use either a full retrospective or a modified retrospective approach to adopt this guidance. The Company is evaluating which transition approach to use and its impact, if any, on its consolidated financial statements.
In August 2014, the FASB issued authoritative accounting guidance related to an entity’s ability to continue as a going concern. This guidance will explicitly require management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. The new standard is effective for annual reporting periods ending after December 15, 2016 and early adoption is permitted. The Company intends to adopt this guidance at the beginning of its first quarter of fiscal year 2016 and does not expect it to have a material impact on its consolidated financial statements and related disclosures.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investment Securities	3. Investment Securities
	Investment securities, all classified as available-for-sale, consisted of the following (in thousands):
		December 31, 2014
		Amortized		Unrealized		Unrealized			Estimated
		Cost		Gains		Losses			Fair
									Value
	U.S. Treasury notes	$	2,748	$	2	$	—		$	2,750
	Government sponsored enterprise securities		97,237		8		(10	)		97,235
	Corporate debt securities		137,682		3		(37	)		137,648
	Commercial paper		22,980		19		—			22,999
		$	260,647	$	32	$	(47	)	$	260,632
		December 31, 2013
		Amortized		Unrealized		Unrealized			Estimated
		Cost		Gains		Losses			Fair
									Value
	U.S. Treasury notes	$	2,743	$	4	$	—		$	2,747
	Government sponsored enterprise securities		78,537		28		(5	)		78,560
	Corporate debt securities		65,290		1		(9	)		65,282
	Commercial paper		27,468		26		—			27,494
		$	174,038	$	59	$	(14	)	$	174,083
	The Company has classified all of its available-for-sale investment securities, including those with maturities beyond one year, as current assets on its consolidated balance sheets based on the highly liquid nature of the investment securities and because these investment securities are considered available for use in current operations. As of December 31, 2014, all of the Company’s available-for-sale investment securities had contractual maturity dates less than one year. As of December 31, 2013, the Company held $33.5 million of available-for-sale investment securities with contractual maturity dates more than one year and less than two years.
	At each reporting date, the Company performs an evaluation of impairment to determine if the unrealized losses are other-than-temporary. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition of the issuer, and the Company’s intent and ability to hold the investment until recovery of its amortized cost basis. The Company intends, and has the ability, to hold its investments in unrealized loss positions until their amortized cost basis has been recovered. Based on its evaluation, the Company determined that its unrealized losses were not other-than-temporary at December 31, 2014 and 2013.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements
	As of December 31, 2014, the Company held $322.1 million of cash equivalents and available-for-sale investment securities consisting of a money market fund, U.S. Treasury notes, and high quality, marketable debt instruments of corporations, financial institutions and government sponsored enterprises in accordance with the Company’s investment policy. The Company’s investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. All investment securities have a credit rating of at least A3/A- or better, or P-1/A-1 or better, as determined by Moody’s Investors Service or Standard & Poor’s.
	The Company’s cash equivalents and available-for-sale investment securities are classified within the fair value hierarchy as defined by authoritative guidance. The Company obtains the fair value of its Level 2 financial instruments from third party pricing services. The pricing services utilize industry standard valuation models whereby all significant observable inputs, including benchmark yields, reported trades, broker/dealer quotes, issuer spreads, bids, offers, or other market-related data, are observable. The Company validates the prices provided by the third-party pricing services by reviewing their pricing methods and matrices, and obtaining market values from other pricing sources. After completing the validation procedures, the Company did not adjust or override any fair value measurements provided by these pricing services as of December 31, 2014 and 2013, respectively.
	The Company does not hold any securities classified as Level 3, which are securities valued using unobservable inputs. The Company has not transferred any investment securities between the classifications.
	The fair value measurements of the Company’s cash equivalents and available-for-sale investment securities are identified in the following tables (in thousands):
				Fair Value Measurements at
				Reporting Date Using
		December 31,		Quoted Prices		Significant		Significant
		2014		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Cash equivalents:
	Money market fund	$	48,423	$	48,423	$	—	$	—
	Government sponsored enterprise securities		13,000		—		13,000		—
	U.S. Treasury notes		2,750		2,750		—		—
	Government sponsored enterprise securities		97,235		—		97,235		—
	Corporate debt securities		137,648		—		137,648		—
	Commercial paper		22,999		—		22,999		—
		$	322,055	$	51,173	$	270,882	$	—
				Fair Value Measurements at
				Reporting Date Using
		December 31,		Quoted Prices		Significant		Significant
		2013		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Cash equivalents:
	Money market fund	$	11,748	$	11,748	$	—	$	—
	U.S. Treasury notes		2,747		2,747		—		—
	Government sponsored enterprise securities		78,560		—		78,560		—
	Corporate debt securities		65,282		—		65,282		—
	Commercial paper		27,494		—		27,494		—
		$	185,831	$	14,495	$	171,336	$	—

Balance_Sheet_Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components
	Property and equipment, net, consisted of the following (in thousands):
		December 31,
		2014			2013
	Machinery and equipment	$	896		$	875
	Computers and software		862			863
	Leasehold improvements		627			570
	Furniture and fixtures		244			245
	Construction-in-Process		64			—
			2,693			2,553
	Accumulated depreciation and amortization		(2,140	)		(1,974	)
		$	553		$	579
	Depreciation and amortization of property and equipment was $206,000, $79,000, and $109,000 for the years ended December 31, 2014, 2013, and 2012, respectively. During 2014 and 2013, the Company retired $40,000 and $2.8 million, respectively, of fully depreciated property and equipment. During 2012, the Company sold $1.5 million of fully depreciated machinery and equipment for a gain of $252,000.
	Accrued expenses consisted of the following (in thousands):
		December 31,
		2014			2013
	Accrued research and development services	$	7,814		$	4,207
	Accrued compensation and benefits		4,167			1,865
	Accrued consulting and professional fees		1,497			308
	Other		340			172
		$	13,818		$	6,552

Collaborative_Research_and_Lic

Collaborative Research and Licensing Agreements	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Research and Licensing Agreements	6. Collaborative Research and Licensing Agreements
	The Company has been a party to three collaboration agreements with Allergan. The March 2003 collaboration originally provided for a three-year research term, which was extended by the parties through March 2013. Pursuant to this agreement, the Company received an aggregate of $19.5 million in payments, consisting of an upfront payment, research funding and related fees, through the conclusion of the collaboration in March 2013. The Company’s two ongoing collaboration agreements with Allergan involve the development of product candidates in the areas of glaucoma and chronic pain. Under the glaucoma collaboration, the Company had received an aggregate of $9.9 million in payments as of December 31, 2014, and is eligible to receive up to an aggregate of $15.0 million in additional payments per product upon the achievement of development and regulatory milestones. Under the chronic pain collaboration, the Company had received an aggregate of $10.5 million in payments as of December 31, 2014, and is eligible to receive up to an aggregate of $10.0 million in additional payments upon the achievement of development and regulatory milestones. The Company also is eligible to receive royalties on future net product sales worldwide, if any, under each of the two ongoing collaboration agreements with Allergan. The Company recognized revenues, consisting of research funding, milestone and related fees, from its collaboration agreements with Allergan of $40,000, $571,000, and $1.1 million during each of the years ended December 31, 2014, 2013, and 2012.
	In March 2009, the Company entered into a collaboration agreement with Meiji Seika Pharma. In July 2012, the Company and Meiji Seika Pharma jointly decided to discontinue the development program that was being pursued under the collaboration, and the collaboration agreement was terminated pursuant to its terms. Under the collaboration agreement, the Company had received $3.0 million in non-refundable license fees as well as payments for the reimbursement of development costs that it had incurred during the collaboration. Payments received from Meiji Seika Pharma were deferred and recognized as revenues using a contingency-adjusted performance model over the estimated period of the Company’s performance. Upon the termination of this collaboration agreement and the end of the Company’s related performance obligations, the Company recognized as revenue the remaining deferred revenue from this collaboration during the third quarter of 2012. The Company recognized revenues relating to this collaboration of $3.2 million during the year ended December 31, 2012.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity
	Public Offerings
	In March 2014, the Company raised net proceeds of $196.8 million from the sale of 7,360,000 shares of its common stock in a public offering, including 960,000 shares sold pursuant to the exercise in full of the underwriters’ over-allotment option.
	In May 2013, the Company raised net proceeds of $107.9 million from the sale of 9,200,000 shares of its common stock in a public offering, including 1,200,000 shares sold pursuant to the exercise in full of the underwriters’ over-allotment option.
	Private Equity Financings
	In December 2012, the Company raised net proceeds of $80.5 million through the sale of 19,000,000 shares of its common stock at a price of $4.43 per share and the sale of warrants to purchase 500,000 shares of its common stock at a price of $4.42 per warrant share in a private equity financing. The warrants have an exercise price of $0.01 per share and will expire on December 17, 2019. In accordance with authoritative accounting guidance, the warrants’ value of $2.2 million was determined on the date of grant using the Black-Scholes model with the following assumptions: risk free interest rate of 1.1 percent, volatility of 105.8 percent, a 7.0 year term and no dividend yield. These warrants were recorded as a component of stockholders’ equity within additional paid-in capital. Per their terms, the outstanding warrants to purchase 500,000 shares of common stock may not be exercised if the holder’s ownership of the Company’s common stock would exceed 19.99 percent following such exercise. Pursuant to the terms of the private financing, the Company has an effective resale registration statement on file with the SEC covering shares of common stock sold and shares of common stock issuable upon the exercise of the warrants.
	In January 2011, the Company raised net proceeds of $13.9 million through the sale of 12,565,446 units at a price of $1.19375 per unit in a private equity financing. Each unit consisted of one share of the Company’s common stock and a warrant to purchase 0.35 shares of common stock. The warrants have an exercise price of $1.38 per share and will expire on January 11, 2018. In accordance with authoritative accounting guidance, the warrants’ value of $3.3 million was determined on the date of grant using the Black-Scholes model with the following assumptions: risk free interest rate of 2.8 percent, volatility of 99.0 percent, a 7.0 year term and no dividend yield. These warrants were recorded as a component of stockholders’ equity with an equal offsetting amount to stockholders’ equity because the value of the warrants was considered a financing cost. During the year ended December 31, 2013, warrants to purchase 1,759,162 shares of common stock were exercised on a net issuance basis, resulting in the issuance of 1,643,006 shares of common stock. During the year ended December 31, 2012, warrants to purchase 1,172,774 shares of common stock were exercised on a net issuance basis, resulting in the issuance of 874,719 shares of common stock. At December 31, 2014, warrants to purchase 1,465,968 shares of common stock remained outstanding. Pursuant to the terms of the private financing, the Company has an effective resale registration statement on file with the SEC covering shares of common stock sold and shares of common stock issuable upon the exercise of the warrants.
	Other Financing Transactions
	In March 2012, the Company entered into an At-The-Market Issuance Sales Agreement (“ATM Agreement”) with MLV & Co. LLC. During the year ended December 31, 2012, the Company raised gross proceeds of $17.7 million from the sale of 5,347,137 shares of common stock under the ATM Agreement, resulting in net proceeds of $17.1 million after issuance costs.
	Stock Option Plans
	The Company’s 2010 Equity Incentive Plan (the “2010 Plan”) permits the grant of options to directors, officers, other employees, and consultants. In addition, the 2010 Plan permits the grant of stock bonuses, rights to purchase restricted stock, and other stock awards. The exercise price of options granted under the 2010 Plan cannot be less than 100 percent of the fair market value of the common stock on the date of grant and the maximum term of any option is ten years. Options granted under the 2010 Plan generally vest over a four-year period. All shares that remained eligible for grant under the Company’s 2004 Equity Incentive Plan (the “2004 Plan”) at the time of approval of the 2010 Plan were transferred to the 2010 Plan. The 2010 Plan share reserve also has been, and may be, increased by the number of shares that otherwise would have reverted to the 2004 Plan reserve after June 2010. At December 31, 2014, there were 12,561,435 shares of common stock authorized for issuance, of which 4,630,905 shares were available for new grants under the 2010 Plan.
	The 2004 Plan provided for the grant of options to directors, officers, other employees, and consultants. The exercise price of options granted under the 2004 Plan was at 100 percent of the fair market value of the common stock on the date of grant and the maximum term of any option was ten years. Options granted under the 2004 Plan generally vested over a four-year period. The Company’s 1997 stock option plan (the “1997 Plan”) provided for the grant of options to directors, officers, other employees, and consultants prior to the Company’s initial public offering. The exercise price of each option grant was set at the fair market value for the Company’s common stock as determined by the Company’s Board of Directors and each option’s maximum term was ten years. Options granted under the 1997 Plan generally vested over a four-year period.
	Stock option transactions during the year ended December 31, 2014 are presented below:
		Number of			Weighted-		Weighted
		Shares			Average		Average
					Exercise		Remaining
					Prices		Contractual
							Term
	Outstanding at December 31, 2013		7,338,138		$	6.81
	Granted		2,519,500		$	25.32
	Exercised		(1,486,802	)	$	4.31
	Canceled/forfeited		(440,306	)	$	16.11
	Outstanding at December 31, 2014		7,930,530		$	12.65		7.26
	Vested and expected to vest at December 31, 2014		7,577,438		$	12.19		7.17
	Exercisable at December 31, 2014		4,246,262		$	5.51		5.78
	The aggregate intrinsic value of options outstanding and exercisable as of December 31, 2014, is calculated as the difference between the exercise price of the underlying options and the closing market price of the Company’s common stock on that date, which was $31.75. The aggregate intrinsic value of options outstanding and exercisable as of December 31, 2014, was $111.4 million. The aggregate intrinsic value of options exercised during the years ended December 31, 2014, 2013, and 2012 was approximately $30.6 million, $20.7 million, and $650,000, respectively, determined as of the date of exercise. The Company received $6.4 million in cash from options exercised during the year ended December 31, 2014.
	The weighted average fair value of options granted during the years ended December 31, 2014, 2013, and 2012 was approximately $18.90, $12.66, and $1.51, respectively. As of December 31, 2014, total unrecognized compensation cost related to stock options and purchase rights was approximately $45.7 million, and the weighted average period over which this cost is expected to be recognized is 2.9 years.
	Stock-based awards issued to non-employees other than directors are accounted for using a fair value method and are re-measured to fair value at each period end until the earlier of the date that performance by the non-employee is complete or a performance commitment has been obtained. The fair value of each award is estimated using the Black-Scholes option pricing model with the following assumptions for the year ended December 31, 2013: dividend yield of 0 percent; volatility of 93 to 95 percent; risk free interest rate of 2 to 3 percent and remaining contractual life of 7 to 10 years. The stock compensation expense related to the grant of stock options to non-employees was $584,000 for the year ended December 31, 2013, and was not significant for the years ended December 31, 2014 and 2012.
	Employee Stock Purchase Plan
	The Company’s 2004 Employee Stock Purchase Plan (the “Purchase Plan”) became effective upon the closing of the Company’s initial public offering in June 2004. The Purchase Plan included an “evergreen” provision providing that a limited number of additional shares may be added to the shares authorized for issuance on the date of each annual meeting of stockholders for a period of ten years, which ended with the meeting in 2014. Through December 31, 2014, a total of 1,525,000 shares of common stock had been reserved for issuance under the Purchase Plan. At December 31, 2014, 385,489 shares of common stock remained available for issuance pursuant to the Purchase Plan. Eligible employees who elect to participate in an offering under the Purchase Plan may have up to 15 percent of their earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the Purchase Plan. The price of common stock purchased under the Purchase Plan is equal to 85 percent of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant purchase date. During the years ended December 31, 2014, 2013, and 2012, a total of 97,911, 122,853, and 205,862 shares of common stock were issued under the Purchase Plan at average prices of $6.78, $2.92, and $0.60, respectively. The weighted average fair value of purchase rights granted during the years ended December 31, 2014, 2013, and 2012 was $11.09, $10.96, and $2.43, respectively. During the years ended December 31, 2014, 2013, and 2012, the Company recorded cash received from the exercise of purchase rights of $664,000, $358,000, and $123,000, respectively.
	Common Stock Reserved for Future Issuance
	At December 31, 2014, a total of 7,930,530 and 1,965,968 shares of common stock were reserved for issuance pursuant to outstanding stock options and warrants, respectively.

401k_Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
401(k) Plan	8. 401(k) Plan
	Effective January 1997, the Company established a deferred compensation plan (the “401(k) Plan”) pursuant to Section 401(k) of the Internal Revenue Code of 1986, as amended (the “Code”), whereby substantially all employees are eligible to contribute up to 60 percent of their pretax earnings, not to exceed amounts allowed under the Code. The Company makes discretionary contributions to the 401(k) Plan equal to 100 percent of each employee’s pretax contributions up to 5 percent of his or her eligible compensation, subject to limitations under the Code. The Company’s total contributions to the 401(k) Plan were $489,000, $240,000, and $180,000 for the years ended December 31, 2014, 2013, and 2012, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes
	At December 31, 2014, the Company had both federal and state net operating loss (“NOL”) carryforwards of approximately $462.8 million and $431.7 million, respectively. Utilization of the NOL and research and development (“R&D”) credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred or that could occur in the future, as required by Section 382 of the Code, as well as similar state and foreign provisions. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders or public groups.
	The Company previously completed a study to assess whether an ownership change, as defined by Section 382 of the Code, had occurred from the Company’s formation through December 31, 2013. Based upon this study, the Company determined that several ownership changes had occurred. Accordingly, the Company reduced its deferred tax assets related to the federal NOL carryforwards and the federal R&D credit carryforwards that are anticipated to expire unused as a result of these ownership changes. These tax attributes were excluded from deferred tax assets with a corresponding reduction of the valuation allowance with no net effect on income tax expense or the effective tax rate. The Company completed a study through December 31, 2014 during the current year and concluded no additional ownership changes occurred. Future ownership changes may further limit the Company’s ability to utilize its remaining tax attributes.
	Federal and state NOL carryforwards of $3.6 million and $17.9 million will expire in 2018 and 2015, respectively, unless utilized. The remaining federal and state NOL carryforwards will begin to expire in 2019 and 2016, respectively. At December 31, 2014, the Company had $9.7 million of federal R&D credit carryforwards of which $119,000 will expire in 2018 unless utilized, and the remaining federal R&D credit carryforwards will begin to expire in 2019. At December 31, 2014, the Company had $6.1 million of state R&D credit carryforwards that have no expiration date. At December 31, 2014, the Company also had foreign NOL carryforwards of approximately $3.7 million that have no expiration date. The Company continues to record the deferred tax assets related to these attributes, subject to valuation allowance, until expiration occurs.
	Approximately $36.8 million of the NOL carryforwards relate to excess tax deductions for stock compensation, the income tax benefit of which will be recorded as additional paid-in capital if and when realized.
	The components of the deferred tax assets are as follows (in thousands):
		2014			2013
	NOL carryforwards	$	168,778		$	136,583
	R&D credit carryforwards		13,668			11,227
	Capitalized R&D		6,548			8,003
	Stock-based compensation		6,630			3,221
	Other		1,615			1,207
			197,239			160,241
	Valuation allowance		(197,239	)		(160,241	)
		$	—		$	—
	Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $37.0 million in 2014 primarily due to an increase in deferred tax assets generated from net operating losses and R&D credits, partially offset by the expiration of NOL carryforwards in 2014.
	A reconciliation of income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows (in thousands):
		2014			2013			2012
	Amounts computed at statutory federal rate	$	(31,441	)	$	(12,902	)	$	(7,088	)
	Stock-based compensation and other permanent differences		1,417			244			209
	Reduction of deferred tax assets under Section 382 of the Code		—			2,781			—
	R&D credits		(2,420	)		(1,269	)		(937	)
	Change in valuation allowance		37,106			13,509			8,375
	State taxes		(5,092	)		(2,140	)		(1,171	)
	Foreign taxes		4			—			(4	)
	Other		426			(223	)		616
		$	0		$	0		$	0
	The tax years 1998-2013 remain open to examination by the major taxing jurisdictions to which the Company is subject. During 2012, the Internal Revenue Service concluded an exam for tax years 2008 and 2009 that resulted in favorable adjustments to the Company’s R&D credits. As of December 31, 2014 and 2013, the Company did not have any liabilities recorded for uncertain tax positions.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies
	Leases
	The Company leases facilities and certain equipment under noncancelable operating leases that expire at various dates through February 2019. Under the terms of the facilities leases, the Company is required to pay its proportionate share of property taxes, insurance and normal maintenance costs.
	Future noncancelable minimum payment obligations under operating lease arrangements, including facilities and equipment, were as follows at December 31, 2014 (in thousands):
	2015	$	2,119
	2016		2,021
	2017		1,455
	2018		1,506
	2019		260
	Thereafter		—
		$	7,361
	Rent expense for operating leases is recorded on a straight-line basis over the life of the lease term. Facility operating leases contain fixed and determinable escalation clauses. The difference between the rent expense and the rent paid is recorded as deferred rent. Rent expense under the Company’s facility and equipment leases was $1.2 million, $594,000, and $663,000, for the years ended December 31, 2014, 2013, and 2012, respectively.
	External Services
	The Company has entered into agreements with contract research organizations and other external service providers primarily for services in connection with the development and planned commercialization of its product candidates. The Company was contractually obligated for up to approximately $16.3 million of future services under these agreements as of December 31, 2014. The nature of the work being conducted under the Company’s agreements with external service providers is such that, in most cases, the services may be stopped with short notice. In such event, the Company would not be liable for the full amount of the contract. The Company’s actual contractual obligations may vary depending upon several factors, including the progress and results of the underlying studies.
	Contingent Regulatory Milestone Payments
	In connection with the Company’s 2006 license agreement with the Ipsen Group, the Company may be obligated in future periods to make certain regulatory milestone payments. These milestone payments may never occur as they are contingent on the achievement of future regulatory events which may never be attained. These one-time payments include $2.5 million payable upon the successful filing of the first regulatory application with the U.S. Food and Drug Administration (“FDA”) and $8.0 million payable upon obtaining the first regulatory approval from the FDA. The Company would also be required to make royalty payments of up to two percent on net product sales, if any.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	11. Selected Quarterly Financial Data (Unaudited)
	The following financial information reflects all normal recurring adjustments, which are, in the opinion of management, necessary for a fair statement of the results of the interim periods. Summarized quarterly data for the years ended December 31, 2014 and 2013 are as follows (in thousands, except per share data):
			Fiscal Year 2014 Quarters
			1st			2nd			3rd			4th			Total
	Revenues		$	30		$	28		$	15		$	47		$	120
	Net loss		$	(17,828	)	$	(21,495	)	$	(24,786	)	$	(28,366	)	$	(92,475	)
	Basic and diluted net loss per share(1)		$	(0.19	)	$	(0.22	)	$	(0.25	)	$	(0.28	)	$	(0.95	)
			Fiscal Year 2013 Quarters
			1st			2nd			3rd			4th			Total
	Revenues		$	417		$	451		$	240		$	37		$	1,145
	Net loss		$	(6,123	)	$	(9,081	)	$	(10,695	)	$	(12,049	)	$	(37,948	)
	Basic and diluted net loss per share(1)		$	(0.08	)	$	(0.11	)	$	(0.12	)	$	(0.13	)	$	(0.44	)
	-1	Net loss per common share, basic and diluted, are computed independently for each quarter and the full year based upon respective average shares outstanding. Therefore, the sum of the quarterly net loss per common share amounts may not equal the annual amounts reported.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries located in Europe. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investments with an initial maturity date at the date of purchase of three months or less to be cash equivalents.
Investment Securities	Investment Securities
	The Company has classified all of its investment securities as available-for-sale and, accordingly, carries these investments at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity. The cost of investment securities classified as available-for-sale is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. Realized gains and losses, if any, are also included in interest income. The cost of securities sold is based on the specific identification method.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The carrying values of the Company’s financial instruments, consisting of cash and cash equivalents, interest and other receivables, and accounts payable and accrued expenses, approximate fair value due to the relative short-term nature of these instruments.
	As disclosed in Note 4, the Company classifies its cash equivalents and available-for-sale investment securities within the fair value hierarchy as defined by authoritative guidance:
	Level 1 Inputs		—		Quoted prices for identical instruments in active markets.
	Level 2 Inputs		—		Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable.
	Level 3 Inputs		—		Valuation derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.
Property and Equipment	Property and Equipment
	Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight line method. Leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the lease by use of the straight line method. Construction-in-process reflects amounts incurred for property, equipment or improvements that have not been placed in service. Maintenance and repair costs are expensed as incurred. When assets are retired or sold, the assets and accumulated depreciation are removed from the respective accounts and any gain or loss is recognized.
	Estimated useful lives by major asset category are as follows:
		Useful Lives
	Machinery and equipment		5 to 7 years
	Computers and software		3 years
	Furniture and fixtures		10 years
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
	The Company reviews its long lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. No such impairment losses have been recorded by the Company.
Revenues	Revenues
	The Company recognizes revenues in accordance with authoritative guidance established by GAAP. The Company’s revenues are primarily related to its collaboration agreements, which may provide for various types of payments, including upfront payments, funding of research and development, milestone payments, and licensing fees. The Company’s collaboration agreements also include potential payments for product royalties; however, the Company has not received any product royalties to date.
	The Company considers a variety of factors in determining the appropriate method of accounting under its collaboration agreements, including whether the various elements can be separated and accounted for individually as separate units of accounting. Where there are multiple deliverables identified within a collaboration agreement that are combined into a single unit of accounting, revenues are deferred and recognized over the expected period of performance. The specific methodology for the recognition of the revenue is determined on a case-by-case basis according to the facts and circumstances of the applicable agreement.
	Upfront, non-refundable payments that do not have stand-alone value are recorded as deferred revenue once received and recognized as revenues over the expected period of performance. Revenues from non-refundable license fees are recognized upon receipt of the payment if the license has stand-alone value, the Company does not have ongoing involvement or obligations, and the Company can determine the best estimate of the selling price for any undelivered items. When non-refundable license fees do not meet all of these criteria, the license revenues are recognized over the expected period of performance. Non-refundable payments for research funding are generally recognized as revenues over the period the related research activities are performed. Payments for reimbursement of external development costs are generally recognized as revenues using a contingency-adjusted performance model over the expected period of performance. Payments received from grants are recognized as revenues as the related research and development is performed and when collectability has been reasonably assured.
	The Company evaluates milestone payments on an individual basis and recognizes revenues from non-refundable milestone payments when the earnings process is complete and collectability is reasonably assured. Non-refundable milestone payments related to arrangements under which the Company has continuing performance obligations are recognized as revenues upon achievement of the associated milestone, provided that (i) the milestone event is substantive and its achievability was not reasonably assured at the inception of the agreement and (ii) the amount of the milestone payment is reasonable in relation to the effort expended or the risk associated with the milestone event. Where separate milestone payments do not meet these criteria, the Company recognizes revenue using a contingency-adjusted performance model over the expected period of performance.
Research and Development Expenses	Research and Development Expenses
	Research and development expenses are charged to operations as incurred. Research and development expenses include, among other things, costs associated with services provided by contract organizations for preclinical development, manufacturing of product candidates, and clinical trials. The Company accrues for costs incurred as the services are being provided by monitoring the status of the trial or services provided and the invoices received from its external service providers. In the case of clinical trials, a portion of the estimated cost normally relates to the projected cost to treat a patient in the trials, and this cost is recognized based on the number of patients enrolled in the trial. Other indirect costs are generally recognized on a straight-line basis over the estimated period of the study. As actual costs become known, the Company adjusts its accruals. Certain research and development programs are funded under agreements with collaboration partners, and the Company’s costs related to these activities are included in research and development expenses.
Concentrations of Risk	Concentrations of Risk
	Financial instruments, which potentially subject the Company to concentrations of credit risk, principally consist of cash, cash equivalents, and investment securities. The Company currently invests its excess cash primarily in a money market fund, U.S. Treasury notes, and high quality, marketable debt instruments of corporations, financial institutions and government sponsored enterprises in accordance with the Company’s investment policy. The Company’s investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. All investment securities have a credit rating of at least A3/A- or better, or P-1/A-1 or better, as determined by Moody’s Investors Service or Standard & Poor’s.
	During the years ended December 31, 2014, 2013 and 2012, revenues from the Company’s agreements with certain collaborative partners exceeded 10 percent of its total revenues. During the year ended December 31, 2014, revenues from Fast Forward, LLC and Allergan, Inc. comprised 59 percent and 33 percent of total revenues, respectively. During the year ended December 31, 2013, revenues from Allergan, the National Institutes of Health, and The Michael J. Fox Foundation comprised 50 percent, 19 percent, and 15 percent of total revenues, respectively. During the year ended December 31, 2012, revenues from Allergan and Meiji Seika Pharma Co., Ltd. comprised 23 percent and 66 percent of total revenues, respectively.
	The Company does not currently have any of its own manufacturing facilities, and therefore relies on third-party manufacturers to produce its product candidates for clinical trials. Although there are potential sources of supply other than the Company’s existing suppliers, any new supplier would be required to qualify under applicable regulatory requirements.
Stock-Based Compensation	Stock-Based Compensation
	The fair value of each employee stock option and each employee stock purchase right granted is estimated on the grant date under the fair value method using the Black-Scholes valuation model. The estimated fair value of each stock option and purchase right, including the effect of estimated forfeitures, is then expensed over the requisite service period, which is generally the vesting period. The following assumptions were used during these periods:
		Years Ended December 31,
		2014			2013			2012
	Stock Options:
	Expected volatility		93	%		94	%		98-99	%
	Risk-free interest rate		2-Jan	%		2-Jan	%		1	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		5.7			6			5.8-6.0
		Years Ended December 31,
		2014			2013			2012
	Employee Stock Purchase Plan:
	Expected volatility		44-95	%		69-118	%		69-137	%
	Risk-free interest rate		0.1-0.5	%		0.1-0.3	%		0.1-0.3	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		0.5-2.0			0.5-2.0			0.5-2.0
	Expected Volatility. The Company considers its historical volatility and implied volatility when determining the expected volatility.
	Risk-Free Interest Rate. The Company determines its risk-free interest rate assumption based on the U.S. Treasury yield for obligations with contractual terms similar to the expected term of the stock option or purchase right being valued.
	Expected Dividend Yield. The Company has never paid any dividends and currently has no plans to do so.
	Expected Life of Options. The Company considers, among other factors, its historical exercise experience to date as well as the mean time remaining to full vesting of all outstanding options and the mean time remaining to the end of the contractual term of all outstanding options.
Income Taxes	Income Taxes
	Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. A deferred income tax asset or liability is computed for the expected future impact of differences between the financial reporting and income tax bases of assets and liabilities and for the expected future tax benefit to be derived from tax credits and loss carryforwards. Deferred income tax expense or benefit represents the net change during the year in the deferred income tax asset or liability. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized.
Net Loss Per Share	Net Loss Per Share
	Net loss per share is presented as basic and diluted net loss per share. Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss by the weighted average number of common shares and common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, stock options and warrants are considered to be common stock equivalents but are not included in the calculations of diluted net loss per share for the periods presented as their effect would be antidilutive.
	Shares used in calculating basic and diluted net loss per common share exclude the following potential common shares as their effect is antidilutive (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Antidilutive options to purchase common stock		7,773			7,245			6,868
	Antidilutive warrants to purchase common stock		1,966			3,116			4,388
			9,739			10,361			11,256
Segment Reporting	Segment Reporting
	Management has determined that the Company operates in one business segment. All revenues for the years ended December 31, 2014, 2013 and 2012 were generated in the United States.
Recently Issued Accounting Standards	Recently Issued Accounting Standards
	In May 2014, the Financial Accounting Standards Board issued authoritative accounting guidance related to revenue from contracts with customers. This guidance is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This guidance is effective for annual reporting periods beginning after December 15, 2016 and early adoption is not permitted. The Company will adopt this guidance on January 1, 2017. Companies may use either a full retrospective or a modified retrospective approach to adopt this guidance. The Company is evaluating which transition approach to use and its impact, if any, on its consolidated financial statements.
	In August 2014, the FASB issued authoritative accounting guidance related to an entity’s ability to continue as a going concern. This guidance will explicitly require management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. The new standard is effective for annual reporting periods ending after December 15, 2016 and early adoption is permitted. The Company intends to adopt this guidance at the beginning of its first quarter of fiscal year 2016 and does not expect it to have a material impact on its consolidated financial statements and related disclosures.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives by Major Asset Category	Estimated useful lives by major asset category are as follows:
		Useful Lives
	Machinery and equipment		5 to 7 years
	Computers and software		3 years
	Furniture and fixtures		10 years
Assumptions Used to Estimate Fair Value of Employee Stock Options	The estimated fair value of each stock option and purchase right, including the effect of estimated forfeitures, is then expensed over the requisite service period, which is generally the vesting period. The following assumptions were used during these periods:
		Years Ended December 31,
		2014			2013			2012
	Stock Options:
	Expected volatility		93	%		94	%		98-99	%
	Risk-free interest rate		2-Jan	%		2-Jan	%		1	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		5.7			6			5.8-6.0
Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan Rights
		Years Ended December 31,
		2014			2013			2012
	Employee Stock Purchase Plan:
	Expected volatility		44-95	%		69-118	%		69-137	%
	Risk-free interest rate		0.1-0.5	%		0.1-0.3	%		0.1-0.3	%
	Expected dividend yield		0	%		0	%		0	%
	Expected life of options in years		0.5-2.0			0.5-2.0			0.5-2.0
Potential Common Shares Excluded in Calculating Basic and Diluted Net Loss Per Common Share	Shares used in calculating basic and diluted net loss per common share exclude the following potential common shares as their effect is antidilutive (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Antidilutive options to purchase common stock		7,773			7,245			6,868
	Antidilutive warrants to purchase common stock		1,966			3,116			4,388
			9,739			10,361			11,256

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investment Securities, All Classified as Available-for-Sale	Investment securities, all classified as available-for-sale, consisted of the following (in thousands):
		December 31, 2014
		Amortized		Unrealized		Unrealized			Estimated
		Cost		Gains		Losses			Fair
									Value
	U.S. Treasury notes	$	2,748	$	2	$	—		$	2,750
	Government sponsored enterprise securities		97,237		8		(10	)		97,235
	Corporate debt securities		137,682		3		(37	)		137,648
	Commercial paper		22,980		19		—			22,999
		$	260,647	$	32	$	(47	)	$	260,632
		December 31, 2013
		Amortized		Unrealized		Unrealized			Estimated
		Cost		Gains		Losses			Fair
									Value
	U.S. Treasury notes	$	2,743	$	4	$	—		$	2,747
	Government sponsored enterprise securities		78,537		28		(5	)		78,560
	Corporate debt securities		65,290		1		(9	)		65,282
	Commercial paper		27,468		26		—			27,494
		$	174,038	$	59	$	(14	)	$	174,083

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements of Cash Equivalents and Available-For-Sale Investment Securities	The fair value measurements of the Company’s cash equivalents and available-for-sale investment securities are identified in the following tables (in thousands):
				Fair Value Measurements at
				Reporting Date Using
		December 31,		Quoted Prices		Significant		Significant
		2014		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Cash equivalents:
	Money market fund	$	48,423	$	48,423	$	—	$	—
	Government sponsored enterprise securities		13,000		—		13,000		—
	U.S. Treasury notes		2,750		2,750		—		—
	Government sponsored enterprise securities		97,235		—		97,235		—
	Corporate debt securities		137,648		—		137,648		—
	Commercial paper		22,999		—		22,999		—
		$	322,055	$	51,173	$	270,882	$	—
				Fair Value Measurements at
				Reporting Date Using
		December 31,		Quoted Prices		Significant		Significant
		2013		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Cash equivalents:
	Money market fund	$	11,748	$	11,748	$	—	$	—
	U.S. Treasury notes		2,747		2,747		—		—
	Government sponsored enterprise securities		78,560		—		78,560		—
	Corporate debt securities		65,282		—		65,282		—
	Commercial paper		27,494		—		27,494		—
		$	185,831	$	14,495	$	171,336	$	—

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Property and Equipment, Net	Property and equipment, net, consisted of the following (in thousands):
		December 31,
		2014			2013
	Machinery and equipment	$	896		$	875
	Computers and software		862			863
	Leasehold improvements		627			570
	Furniture and fixtures		244			245
	Construction-in-Process		64			—
			2,693			2,553
	Accumulated depreciation and amortization		(2,140	)		(1,974	)
		$	553		$	579
Accrued Expenses	Accrued expenses consisted of the following (in thousands):
		December 31,
		2014			2013
	Accrued research and development services	$	7,814		$	4,207
	Accrued compensation and benefits		4,167			1,865
	Accrued consulting and professional fees		1,497			308
	Other		340			172
		$	13,818		$	6,552

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stock Option Transactions	Stock option transactions during the year ended December 31, 2014 are presented below:
		Number of			Weighted-		Weighted
		Shares			Average		Average
					Exercise		Remaining
					Prices		Contractual
							Term
	Outstanding at December 31, 2013		7,338,138		$	6.81
	Granted		2,519,500		$	25.32
	Exercised		(1,486,802	)	$	4.31
	Canceled/forfeited		(440,306	)	$	16.11
	Outstanding at December 31, 2014		7,930,530		$	12.65		7.26
	Vested and expected to vest at December 31, 2014		7,577,438		$	12.19		7.17
	Exercisable at December 31, 2014		4,246,262		$	5.51		5.78

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Components of Deferred Tax Assets	The components of the deferred tax assets are as follows (in thousands):
		2014			2013
	NOL carryforwards	$	168,778		$	136,583
	R&D credit carryforwards		13,668			11,227
	Capitalized R&D		6,548			8,003
	Stock-based compensation		6,630			3,221
	Other		1,615			1,207
			197,239			160,241
	Valuation allowance		(197,239	)		(160,241	)
		$	—		$	—
Reconciliation of Income Taxes to Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss	A reconciliation of income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows (in thousands):
		2014			2013			2012
	Amounts computed at statutory federal rate	$	(31,441	)	$	(12,902	)	$	(7,088	)
	Stock-based compensation and other permanent differences		1,417			244			209
	Reduction of deferred tax assets under Section 382 of the Code		—			2,781			—
	R&D credits		(2,420	)		(1,269	)		(937	)
	Change in valuation allowance		37,106			13,509			8,375
	State taxes		(5,092	)		(2,140	)		(1,171	)
	Foreign taxes		4			—			(4	)
	Other		426			(223	)		616
		$	0		$	0		$	0

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future Noncancelable Minimum Payment Obligations under Operating Lease Arrangements, Including Facilities and Equipment	Future noncancelable minimum payment obligations under operating lease arrangements, including facilities and equipment, were as follows at December 31, 2014 (in thousands):
	2015	$	2,119
	2016		2,021
	2017		1,455
	2018		1,506
	2019		260
	Thereafter		—
		$	7,361

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data
			Fiscal Year 2014 Quarters
			1st			2nd			3rd			4th			Total
	Revenues		$	30		$	28		$	15		$	47		$	120
	Net loss		$	(17,828	)	$	(21,495	)	$	(24,786	)	$	(28,366	)	$	(92,475	)
	Basic and diluted net loss per share(1)		$	(0.19	)	$	(0.22	)	$	(0.25	)	$	(0.28	)	$	(0.95	)
			Fiscal Year 2013 Quarters
			1st			2nd			3rd			4th			Total
	Revenues		$	417		$	451		$	240		$	37		$	1,145
	Net loss		$	(6,123	)	$	(9,081	)	$	(10,695	)	$	(12,049	)	$	(37,948	)
	Basic and diluted net loss per share(1)		$	(0.08	)	$	(0.11	)	$	(0.12	)	$	(0.13	)	$	(0.44	)
	-1	Net loss per common share, basic and diluted, are computed independently for each quarter and the full year based upon respective average shares outstanding. Therefore, the sum of the quarterly net loss per common share amounts may not equal the annual amounts reported.

Organization_and_Nature_of_Ope1

Organization and Nature of Operations - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	($498,143)	($405,668)

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives by Major Asset Category (Detail)	12 Months Ended
	Dec. 31, 2014
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	5 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	7 years
Computers And Software
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	10 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policy [Line Items]
Impairment losses	0
Number of business segments	1
Revenues | Fast Forward, LLC
Summary Of Significant Accounting Policy [Line Items]
Percentage of revenues from collaborative partners to total revenues	59.00%
Revenues | Allergan, Inc.
Summary Of Significant Accounting Policy [Line Items]
Percentage of revenues from collaborative partners to total revenues	33.00%	50.00%	23.00%
Revenues | National Institutes of Health
Summary Of Significant Accounting Policy [Line Items]
Percentage of revenues from collaborative partners to total revenues		19.00%
Revenues | Meiji Seika Pharma Co., Ltd.
Summary Of Significant Accounting Policy [Line Items]
Percentage of revenues from collaborative partners to total revenues			66.00%
Revenues | Michael J. Fox Foundation
Summary Of Significant Accounting Policy [Line Items]
Percentage of revenues from collaborative partners to total revenues		15.00%

Assumptions_Used_to_Estimate_F

Assumptions Used to Estimate Fair Value of Employee Stock Options (Detail) (Stock Options)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assumptions used to Determine Fair Value Options [Line Items]
Expected volatility	93.00%	94.00%
Expected volatility, minimum			98.00%
Expected volatility, maximum			99.00%
Risk-free interest rate			1.00%
Risk-free interest rate, minimum	1.00%	1.00%
Risk-free interest rate, maximum	2.00%	2.00%
Expected dividend yield	0.00%	0.00%	0.00%
Expected life of options in years	5 years 8 months 12 days	6 years
Minimum
Assumptions used to Determine Fair Value Options [Line Items]
Expected life of options in years			5 years 9 months 18 days
Maximum
Assumptions used to Determine Fair Value Options [Line Items]
Expected life of options in years			6 years

Assumptions_Used_to_Estimate_F1

Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan Rights (Detail) (Employee Stock Purchase Plan)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Stock Purchase Plan [Line Items]
Expected volatility, minimum	44.00%	69.00%	69.00%
Expected volatility, maximum	95.00%	118.00%	137.00%
Risk-free interest rate, minimum	0.10%	0.10%	0.10%
Risk-free interest rate, maximum	0.50%	0.30%	0.30%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Employee Stock Purchase Plan [Line Items]
Expected life of options in years	6 months	6 months	6 months
Maximum
Employee Stock Purchase Plan [Line Items]
Expected life of options in years	2 years	2 years	2 years

Potential_Common_Shares_Exclud

Potential Common Shares Excluded in Calculating Basic and Diluted Net Loss Per Common Share (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	9,739	10,361	11,256
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	7,773	7,245	6,868
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	1,966	3,116	4,388

Investment_Securities_All_Clas

Investment Securities, All Classified as Available-for-Sale (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Amortized Cost	$260,647	$174,038
Unrealized Gains	32	59
Unrealized Losses	-47	-14
Estimated Fair Value	260,632	174,083
U.S. Treasury notes
Schedule of Investments [Line Items]
Amortized Cost	2,748	2,743
Unrealized Gains	2	4
Estimated Fair Value	2,750	2,747
Government sponsored enterprise securities
Schedule of Investments [Line Items]
Amortized Cost	97,237	78,537
Unrealized Gains	8	28
Unrealized Losses	-10	-5
Estimated Fair Value	97,235	78,560
Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	137,682	65,290
Unrealized Gains	3	1
Unrealized Losses	-37	-9
Estimated Fair Value	137,648	65,282
Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	22,980	27,468
Unrealized Gains	19	26
Estimated Fair Value	$22,999	$27,494

Investment_Securities_Addition

Investment Securities - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Investment securities, available-for-sale	$260,632	$174,083
Maturity Dates More Than 1 and Less Than 2 Years
Schedule of Investments [Line Items]
Investment securities, available-for-sale		$33,500

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Disclosures [Abstract]
Investment, fair value disclosure	$322,055	$185,831

Fair_Value_Measurements_of_Cas

Fair Value Measurements of Cash Equivalents and Available-For-Sale Investment Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	$322,055	$185,831
Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value disclosure	48,423	11,748
Government sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value disclosure	13,000
Available-for-sale investment securities, fair value disclosure	97,235	78,560
U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	2,750	2,747
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	137,648	65,282
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	22,999	27,494
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	51,173	14,495
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value disclosure	48,423	11,748
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	2,750	2,747
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	270,882	171,336
Significant Other Observable Inputs (Level 2) | Government sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value disclosure	13,000
Available-for-sale investment securities, fair value disclosure	97,235	78,560
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	137,648	65,282
Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	$22,999	$27,494

Property_and_Equipment_Net_Det

Property and Equipment, Net (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$2,693	$2,553
Accumulated depreciation and amortization	-2,140	-1,974
Property and equipment, net	553	579
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	896	875
Computers And Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	862	863
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	627	570
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	244	245
Construction-in-Process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$64

Balance_Sheet_Components_Addit

Balance Sheet Components - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and amortization of property and equipment	$206,000	$79,000	$109,000
Removal of fully depreciated property, machinery and equipment	40,000	2,800,000	1,500,000
Gain on sale of machinery and equipment		$10,000	$252,000

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Accrued research and development services	$7,814	$4,207
Accrued compensation and benefits	4,167	1,865
Accrued consulting and professional fees	1,497	308
Other	340	172
Accrued expenses	$13,818	$6,552

Collaborative_Research_and_Lic1

Collaborative Research and Licensing Agreements - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenues	$47,000	$15,000	$28,000	$30,000	$37,000	$240,000	$451,000	$417,000	$120,000	$1,145,000	$4,907,000
Allergan, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total number of collaboration agreements									3
Number of ongoing collaboration agreements									2
Collaborative revenues									40,000	571,000	1,100,000
Allergan, Inc. | March 2003 Research Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, payments received								19,500,000
Collaboration agreement, original research term								3 years
Collaboration agreement, termination date								2013-03
Collaboration agreement, beginning date								2003-03
Allergan, Inc. | Glaucoma Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, payments received									9,900,000
Collaboration agreement, estimated development and regulatory milestones	15,000,000								15,000,000
Allergan, Inc. | Chronic Pain Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, payments received									10,500,000
Collaboration agreement, estimated development and regulatory milestones	10,000,000								10,000,000
Meiji Seika Pharma Co., Ltd.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenues											3,200,000
Collaboration agreement, license fees									$3,000,000

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended				12 Months Ended
	Mar. 31, 2014	31-May-13	Dec. 31, 2012	Jan. 31, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Class of Stock [Line Items]
Proceeds from issuance of common stock and warrants, net of issuance costs	$196,800,000	$107,900,000			$203,851,000	$111,682,000	$98,204,000
Share of common stock issued	7,360,000	9,200,000	19,000,000	12,565,446
Proceed from sale of stock and warrants			80,500,000	13,900,000
Common stock sale price per share			$4.43	$1.19
Warrants issued			500,000				500,000
Warrants issuance price per share			$4.42
Warrant exercise price			0.01	1.38			0.01
Issuance of warrant value			2,200,000	3,300,000
Warrant risk free interest rate			1.10%	2.80%
volatility percentage			105.80%	99.00%
Warrant term			7 years	7 years
Warrants outstanding			500,000				500,000
Description of warrant					Per their terms, the outstanding warrants to purchase 500,000 shares of common stock may not be exercised if the holder's ownership of the Company's common stock would exceed 19.99 percent following such exercise.
Number of common stock per unit sold				1
Number of common stock allowed to purchase				0.35
Dividend Yield				0.00%		0.00%
Warrants exercised for purchase of common shares						1,759,162	1,172,774
Issuance of common stock from exercise of warrants on a net issuance basis (in shares)						1,643,006	874,719
Warrants outstanding to purchase common stock					1,465,968
Closing market price of Common stock					$31.75
Aggregate intrinsic value of stock options outstanding and exercisable					111,400,000
Aggregate intrinsic value of stock options exercised					30,600,000	20,700,000	650,000
Cash received from options exercised					6,400,000
Weighted average fair value of options granted					$18.90	$12.66	$1.51
Unrecognized compensation costs					45,700,000
Weighted average period cost expected to be recognized					2 years 10 months 24 days
Stock compensation expense related to non-employee stock options					16,039,000	5,711,000	1,930,000
Number of periods additional number of shares could be added to shares authorized for issuance					10 years
Issuance of common stock pursuant to employee stock purchase plan					97,911	122,853	205,862
Average price of stock issued under purchase plan					$6.78	$2.92	$0.60
Issuance of common stock pursuant to employee stock purchase plan					664,000	358,000	123,000
Common stock reserved for issuance upon exercise of stock options					7,930,530	7,338,138
Common stock reserved for issuance upon exercise of warrants					1,965,968
Minimum
Class of Stock [Line Items]
Warrant risk free interest rate						2.00%
volatility percentage						93.00%
Warrant term						7 years
Maximum
Class of Stock [Line Items]
Warrant risk free interest rate						3.00%
volatility percentage						95.00%
Warrant term						10 years
Expire on December 17, 2019
Class of Stock [Line Items]
Warrant expiration date					12/17/19
Expire on January 11, 2018
Class of Stock [Line Items]
Warrant expiration date					1/11/18
Underwriter
Class of Stock [Line Items]
Share of common stock issued		1,200,000
Stock Options
Class of Stock [Line Items]
Exercise price of Options as percentage of fair market value					100.00%
Stock Options | Equity Incentive Plan 2010
Class of Stock [Line Items]
Exercise price of Options as percentage of fair market value								100.00%
Options maximum expiration term								10 years
Options vesting period								4 years
Number of common stock authorized for issuance					12,561,435
Common stock available for grants					4,630,905
Employee Stock Purchase Plan
Class of Stock [Line Items]
Term of ESPP Evergreen Provision					10 years
Common stock reserved for issuance under stock purchase plan					1,525,000
Common stock remained available for issuance pursuant to the Purchase Plan					385,489
Eligible employees percentage of earnings withheld to purchase shares under purchase plan					15.00%
Purchase price of common stock as percentage of market value					85.00%
Weighted average fair value of purchase rights granted					$11.09	$10.96	$2.43
Non Employee Stock [Member]
Class of Stock [Line Items]
Stock compensation expense related to non-employee stock options						584,000
Underwriter
Class of Stock [Line Items]
Share of common stock issued	960,000
At -The-Market Agreement
Class of Stock [Line Items]
Proceeds from issuance of common stock and warrants, net of issuance costs							17,100,000
Share of common stock issued							5,347,137
Gross proceeds from issuance of common stock							$17,700,000

Stock_Option_Transactions_Deta

Stock Option Transactions (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Number of Shares
Option Outstanding, Beginning Balance	7,338,138
Granted	2,519,500
Exercised	-1,486,802
Canceled/forfeited	-440,306
Option Outstanding, Ending Balance	7,930,530
Vested and expected to vest	7,577,438
Exercisable	4,246,262
Weighted Average Exercise Prices
Weighted Average Exercise Prices, Beginning Balance	$6.81
Weighted Average Exercise Prices, granted	$25.32
Weighted Average Exercise Prices, exercised	$4.31
Weighted Average Exercise Prices, Canceled/forfeited	$16.11
Weighted Average Exercise Prices, Ending Balance	$12.65
Weighted Average Exercise Prices, Vested and expected to vest	$12.19
Weighted Average Exercise Prices, Exercisable	$5.51
Weighted average remaining contractual term, outstanding	7 years 3 months 4 days
Weighted average remaining contractual term, Vested and expected to vest	7 years 2 months 1 day
Weighted average remaining contractual term, Exercisable	5 years 9 months 11 days

401_k_Plan_Additional_Informat

401 (k) Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Maximum contribution by employee, percentage of pretax earnings	60.00%
Percentage of company's matching contribution with respect to each participant's contribution	100.00%
Company matching contributions to maximum employees eligible compensation	5.00%
Company contributions to 401 (k) plan	$489,000	$240,000	$180,000

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Federal R&D credit carryforwards	$9,700,000
Net operating loss carryforwards related to excess tax deductions for stock compensation	36,800,000
Increase in valuation allowance of deferred tax assets	37,000,000
Liabilities for uncertain tax positions	0	0
Federal
Income Tax [Line Items]
Operating loss carryforwards	462,800,000
Remaining net operating loss carryforward, expiration year	2019
Federal | Expiring in 2018
Income Tax [Line Items]
Operating loss carryforwards	3,600,000
State
Income Tax [Line Items]
Operating loss carryforwards	431,700,000
Remaining net operating loss carryforward, expiration year	2016
Net operating loss carryforwards with no expiration date	6,100,000
State | Expiring in 2014
Income Tax [Line Items]
Operating loss carryforwards	17,900,000
Expire in 2018
Income Tax [Line Items]
Federal R&D credit carryforwards	119,000
Foreign
Income Tax [Line Items]
Net operating loss carryforwards with no expiration date	$3,700,000

Income_Taxes_Components_of_Def

Income Taxes - Components of Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Disclosure [Abstract]
NOL carryforwards	$168,778	$136,583
R&D credit carryforwards	13,668	11,227
Capitalized R&D	6,548	8,003
Stock-based compensation	6,630	3,221
Other	1,615	1,207
Deferred Tax Assets, Gross	197,239	160,241
Valuation allowance	-197,239	-160,241
Deferred Tax Assets, Net	$0	$0

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Income Taxes to Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Amounts computed at statutory federal rate	($31,441)	($12,902)	($7,088)
Stock-based compensation and other permanent differences	1,417	244	209
Reduction of deferred tax assets under Section 382 of the Code		2,781
R&D credits	-2,420	-1,269	-937
Change in valuation allowance	37,106	13,509	8,375
State taxes	-5,092	-2,140	-1,171
Foreign taxes	4		-4
Other	426	-223	616
Income Tax Expense (Benefit)	$0	$0	$0

Commitment_and_Contingencies_A

Commitment and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Commitments [Line Items]
Operating lease, expiration year	2019-02
Rent expense	$1,200,000	$594,000	$663,000
Payable upon filing of first regulatory application with U.S Food and Drug Administration, ("FDA")
Other Commitments [Line Items]
One-time contingent regulatory milestone payments related to agreement with Ipsen Group	2,500,000
Payable upon obtaining first regulatory approval from the FDA.
Other Commitments [Line Items]
One-time contingent regulatory milestone payments related to agreement with Ipsen Group	8,000,000
Maximum
Other Commitments [Line Items]
Development services	$16,300,000
Percentage of royalty payments obligation on net product sales	2.00%

Commitments_and_Contingencies_1

Commitments and Contingencies - Future Noncancelable Minimum Payment Obligations under Operating Lease Arrangements, Including Facilities and Equipment (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
2015	$2,119
2016	2,021
2017	1,455
2018	1,506
2019	260
Thereafter	0
Operating Leases, Future Minimum Payments Due, Total	$7,361

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Detail) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues	$47		$15		$28		$30		$37		$240		$451		$417		$120		$1,145		$4,907
Net loss	($28,366)		($24,786)		($21,495)		($17,828)		($12,049)		($10,695)		($9,081)		($6,123)		($92,475)		($37,948)		($20,849)
Basic and diluted net loss per share	($0.28)	[1]	($0.25)	[1]	($0.22)	[1]	($0.19)	[1]	($0.13)	[1]	($0.12)	[1]	($0.11)	[1]	($0.08)	[1]	($0.95)	[1]	($0.44)	[1]	($0.38)
[1]	Net loss per common share, basic and diluted, are computed independently for each quarter and the full year based upon respective average shares outstanding. Therefore, the sum of the quarterly net loss per common share amounts may not equal the annual amounts reported.