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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.

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2015	Jan. 29, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	ACAD
Entity Registrant Name	ACADIA PHARMACEUTICALS INC
Entity Central Index Key	0001070494
Current Fiscal Year End Date	--12-31
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		112,636,457
Entity Public Float			$ 2.6

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 102,138	$ 61,854
Investment securities, available-for-sale	112,994	260,632
Interest and other receivables	1,638	964
Prepaid expenses and other current assets	2,219	1,168
Total current assets	218,989	324,618
Property and equipment, net	2,203	553
Restricted cash	375
Other assets	329	287
Total assets	221,896	325,458
Liabilities and stockholders' equity
Accounts payable	1,672	2,016
Accrued liabilities	20,230	13,818
Total current liabilities	21,902	15,834
Long-term liabilities	232	135
Total liabilities	22,134	15,969
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized at December 31, 2015 and 2014; no shares issued and outstanding at December 31, 2015 and 2014
Common stock, $0.0001 par value; 225,000,000 shares and 150,000,000 shares authorized at December 31, 2015 and December 31, 2014, respectively; 101,938,702 shares and 100,047,331 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	10	10
Additional paid-in capital	862,327	807,631
Accumulated deficit	(662,586)	(498,143)
Accumulated other comprehensive income (loss)	11	(9)
Total stockholders' equity	199,762	309,489
Total liabilities and stockholders' equity	$ 221,896	$ 325,458

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	225,000,000	150,000,000
Common stock, shares issued	101,938,702	100,047,331
Common stock, shares outstanding	101,938,702	100,047,331

Consolidated Statements of Operations - USD ($)
shares in Thousands, $ in Thousands

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Revenues

Collaborative revenues

$ 61

$ 120

$ 1,145

Operating expenses

License fees

2,500

Research and development

73,869

60,602

26,722

General and administrative

88,304

32,748

12,720

Total operating expenses

164,673

93,350

39,442

Loss from operations

(164,612)

(93,230)

(38,297)

Interest income, net

499

755

349

Loss before income taxes

(164,113)

(92,475)

(37,948)

Income tax expense

330

Net loss

$ (164,443)

$ (92,475)

$ (37,948)

Net loss per common share, basic and diluted

$ (1.63)

^[1]

$ (0.95)

^[1]

$ (0.44)

Weighted average common shares outstanding, basic and diluted

100,630

97,248

85,715

[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 Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (164,443)	$ (92,475)	$ (37,948)
Other comprehensive gain (loss):
Unrealized gain (loss) on investment securities	13	(60)	45
Foreign currency translation adjustments	7	3	(1)
Comprehensive loss	$ (164,423)	$ (92,532)	$ (37,904)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	$ (164,443)	$ (92,475)	$ (37,948)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	40,194	16,039	5,711
Amortization of premiums and accretion of discounts on investment securities, available for sale	(2,060)	484	1,528
Depreciation	647	206	79
Income tax benefit from exercise of stock options	(247)
Gain on disposal of assets			(10)
Changes in operating assets and liabilities:
Interest and other receivables	(674)	(214)	(505)
Prepaid expenses and other current assets	(804)	652	(1,484)
Restricted cash	(375)
Other assets	(42)	(108)	(179)
Accounts payable	(344)	1,644	(1,003)
Accrued liabilities	6,256	7,266	2,413
Deferred revenue		(55)	(379)
Long-term liabilities	97	127	8
Net cash used in operating activities	(121,795)	(66,434)	(31,769)
Cash flows from investing activities
Purchases of investment securities	(269,486)	(335,361)	(211,585)
Maturities of investment securities	419,197	248,268	86,087
Purchases of property and equipment	(2,141)	(180)	(618)
Proceeds from sales of property and equipment			12
Net cash provided by (used in) investing activities	147,570	(87,273)	(126,104)
Cash flows from financing activities
Proceeds from issuances of equity securities, net of issuance costs	14,547	203,851	111,682
Deferred offering costs	(292)
Income tax benefit from exercise of stock options	247
Net cash provided by financing activities	14,502	203,851	111,682
Effect of exchange rate changes on cash	7	3	(1)
Net increase (decrease) in cash and cash equivalents	40,284	50,147	(46,192)
Cash and cash equivalents at beginning of period	61,854	11,707	57,899
Cash and cash equivalents at end of period	102,138	$ 61,854	$ 11,707
Supplemental disclosure of cash flow information:
Cash paid for income taxes	415
Supplemental disclosure of noncash investing information:
Property and equipment purchases in accrued liabilities	$ 156

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2012		73,334,216
Beginning balance at Dec. 31, 2012	$ 84,984	$ 7	$ 452,693	$ (367,720)	$ 4
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
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 (in shares) at Dec. 31, 2013		91,102,618
Ending balance at Dec. 31, 2013	182,131	$ 9	587,742	(405,668)	48
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
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 (in shares) at Dec. 31, 2014		100,047,331
Ending balance at Dec. 31, 2014	$ 309,489	$ 10	807,631	(498,143)	(9)
Issuance of common stock from exercise of stock options (in shares)	1,822,578	1,822,578
Issuance of common stock from exercise of stock options	$ 12,991		12,991
Issuance of common stock pursuant to employee stock purchase plan (in shares)	68,793	68,793
Issuance of common stock pursuant to employee stock purchase plan	$ 1,556		1,556
Income tax benefit from exercise of stock options	247		247
Deferred offering costs	(292)		(292)
Net loss	(164,443)			(164,443)
Stock-based compensation	40,194		40,194
Other comprehensive income (loss)	20				20
Ending balance (in shares) at Dec. 31, 2015		101,938,702
Ending balance at Dec. 31, 2015	$ 199,762	$ 10	$ 862,327	$ (662,586)	$ 11

Organization and Business	12 Months Ended
Organization and Business	Dec. 31, 2015
Accounting Policies [Abstract]
Organization and Business	1. Organization and Business ACADIA Pharmaceuticals Inc. (the “Company”), based in San Diego, California, is a biopharmaceutical company focused on the development and commercialization of innovative medicines to address unmet medical needs in central nervous system disorders. The Company was originally incorporated in Vermont in 1993 as Receptor Technologies, Inc. and reincorporated in Delaware in 1997.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2015

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 a 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 as the sale of such securities may be required prior to maturity to implement management strategies, 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, restricted cash, and accounts payable and accrued liabilities, 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:

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.

License Fees

The Company expenses amounts paid to acquire licenses associated with products under development when the ultimate recoverability of the amounts paid is uncertain and the technology has no alternative future use when acquired. Acquisitions of technology licenses are charged to expense or capitalized based upon management’s assessment regarding the ultimate recoverability of the amounts paid and the potential for alternative future use. The Company has determined that technological feasibility for its product candidates is reached when the requisite regulatory approvals are obtained to make the product available for sale.

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, pre-commercialization manufacturing expenses, 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 have been 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 invests its excess cash primarily in a money market fund, U.S. Treasury notes, and high quality, marketable debt instruments of corporations 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 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,
	2015			2014			2013
Stock Options:
Expected volatility		89	%		93	%		94	%
Risk-free interest rate		1-2	%		1-2	%		1-2	%
Expected dividend yield		0	%		0	%		0	%
Expected life of options in years		5.7			5.7			6.0

	Years Ended December 31,
	2015			2014			2013
Employee Stock Purchase Plan:
Expected volatility		51-59	%		44-95	%		69-118	%
Risk-free interest rate		0.1-0.9	%		0.1-0.5	%		0.1-0.3	%
Expected dividend yield		0	%		0	%		0	%
Expected life in years		0.5-2.0			0.5-2.0			0.5-2.0

Stock-based awards issued to non-employees other than directors are accounted for under the fair value method using the Black-Scholes valuation model 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 stock-based 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, 2015 and 2014. In 2015, stock options were granted to a non-employee that vest upon the attainment of Company-specific performance criteria. Through December 31, 2015, no expense was recognized related to these performance-based stock options as future vesting was uncertain.

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. In determining the expected life for stock 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. The estimated life for the Company’s employee stock purchase rights is based upon the terms of each offering period.

The table below summarizes the total stock-based compensation expense included in the Company’s statements of operations for the periods presented (in thousands):


	Years Ended December 31,
	2015		2014		2013
Research and development	$	12,171	$	5,191	$	2,208
General and administrative		28,023		10,848		3,503

	$	40,194	$	16,039	$	5,711

During the first quarter of 2015, the Company entered into a transition agreement with its former Chief Executive Officer, in connection with his retirement from the Company in March 2015. Stock-based compensation expense for the year ended December 31, 2015 includes a one-time $9.0 million charge representing the fair value of the outstanding options expected to vest over the term of the transition agreement as valued on the retirement date.

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.

The Company recognizes excess tax benefits associated with stock-based compensation to stockholders’ equity only when realized. When assessing whether excess tax benefits relating to stock-based compensation have been realized, the Company follows the with-and-without approach excluding any indirect effects of the excess tax deductions. Under this approach, excess tax benefits related to stock-based compensation are not deemed to be realized until after the utilization of all other tax benefits available to the Company.

The Company recognizes the impact of a tax position in the financial statements only if that position is more likely than not of being sustained upon examination by taxing authorities, based on the technical merits of the position. Any interest and penalties related to uncertain tax positions will be reflected in income tax expense.

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. The Company incurred net losses for all periods presented and there were no reconciling items for potentially dilutive securities. More specifically, at December 31, 2015, 2014 and 2013, options, employee stock purchase rights, and warrants totaling approximately 11,525,000 shares, 9,902,000 shares and 9,314,000 shares, respectively, were excluded as their effect would have been anti-dilutive.

Segment Reporting

Management has determined that the Company operates in one business segment which is the development and commercialization of innovative medicines. All revenues for the years ended December 31, 2015, 2014 and 2013 were generated in the United States.

Recently Issued Accounting Standards

In November 2015, the Financial Accounting Standards Board (“FASB”) issued authoritative accounting guidance related to the balance sheet classification of deferred taxes. This guidance requires deferred tax liabilities and assets to be classified as noncurrent in a classified statement of financial position. This guidance may be applied on either a prospective or retrospective basis and is effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted. The Company adopted this standard prospectively in the fourth quarter of 2015, and as the Company’s deferred tax assets are fully offset by a valuation allowance, there was no impact to the Company’s financial position or results of operations upon its adoption of this standard.

In May 2014, the FASB 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. The original guidance was effective for annual reporting periods beginning after December 15, 2016. However, in July 2015, the FASB agreed to delay the effective date by one year, with early adoption permitted, but not before the original effective date of the standard. In accordance with the agreed upon delay, the Company will adopt this guidance on January 1, 2018. 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 for annual periods and interim periods thereafter, with early adoption 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

12 Months Ended

Dec. 31, 2015

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, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
U.S. Treasury notes	$	9,000	$	—	$	(1	)	$	8,999
Government sponsored enterprise securities		103,996		12		(13	)		103,995

	$	112,996	$	12	$	(14	)	$	112,994


	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated 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

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, 2015 and 2014. As of December 31, 2015 and 2014, all of the Company’s available-for-sale investment securities had contractual maturity dates of less than one year.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

As of December 31, 2015, the Company held $213.1 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 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’s investment securities classified as Level 1 are valued using quoted market prices. 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 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, 2015 and 2014, 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, 2015		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	46,437	$	46,437	$	—	$	—
U.S. Treasury notes		8,999		8,999		—		—
Government sponsored enterprise securities		157,623		—		157,623		—

	$	213,059	$	55,436	$	157,623	$	—


			Fair Value Measurements at Reporting Date Using
	December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	48,423	$	48,423	$	—	$	—
U.S. Treasury notes		2,750		2,750		—		—
Government sponsored enterprise securities		110,235		—		110,235		—
Corporate debt securities		137,648		—		137,648		—
Commercial paper		22,999		—		22,999		—

	$	322,055	$	51,173	$	270,882	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2015

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,
	2015			2014
Machinery and equipment	$	1,017		$	896
Computers and software		1,336			862
Leasehold improvements		1,413			627
Furniture and fixtures		724			244
Construction-in-process		500			64

		4,990			2,693
Accumulated depreciation		(2,787	)		(2,140	)

	$	2,203		$	553

Depreciation of property and equipment was $647,000, $206,000, and $79,000 for the years ended December 31, 2015, 2014, and 2013, respectively. During 2015, 2014 and 2013, the Company retired $72,000, $40,000 and $2.8 million, respectively, of fully depreciated property and equipment.

Accrued liabilities consisted of the following (in thousands):


	December 31,
	2015		2014
Accrued research and development services	$	8,805	$	7,814
Accrued compensation and benefits		5,722		4,167
Accrued consulting and professional fees		4,508		1,497
Other		1,195		340

	$	20,230	$	13,818

Collaborative Research Agreements	12 Months Ended
Collaborative Research Agreements	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Research Agreements	6. Collaborative Research Agreements The Company has been a party to three collaboration agreements with Allergan. The 2003 collaboration originally provided for a three-year research term, which was extended by the parties through 2013. The 1999 collaboration with Allergan for the development of product candidates in the area of glaucoma was terminated in 2015. The Company’s continuing 1997 collaboration agreement with Allergan involves the development of product candidates in the area of chronic pain. Under the chronic pain collaboration, the Company is eligible to receive up to an aggregate of $10.0 million in 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 the continuing collaboration agreement with Allergan. The Company recognized revenues, consisting of research funding, milestone and related fees, from its collaboration agreements with Allergan of $61,000, $40,000, and $571,000 during each of the years ended December 31, 2015, 2014, and 2013.

Stockholders' Equity

12 Months Ended

Dec. 31, 2015

Equity [Abstract]

Stockholders' Equity

7. Stockholders’ Equity

Authorized Shares

In June 2015, following approval by the Company’s stockholders, the Company filed a Certificate of Amendment of its Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware, which increased the number of authorized shares of common stock of the Company from 150,000,000 to 225,000,000.

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, 2015, 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.

Stock Option Plans

The Company’s 2010 Equity Incentive Plan, as amended to date (the “2010 Plan”), permits the grant of options to employees, directors 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 10 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. In June 2015, the Company’s stockholders approved an amendment to its 2010 Plan to, among other things, increase the aggregate number of shares of common stock authorized for issuance under the plan by 5,000,000 shares, and at December 31, 2015, there were 15,738,857 shares of common stock authorized for issuance, of which 6,195,781 shares were available for new grants under the 2010 Plan.

The 2004 Plan provided for the grant of options to employees, directors 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 10 years. Options granted under the 2004 Plan generally vested over a four-year period.

Stock option transactions during the year ended December 31, 2015 are presented below:


	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2014		7,930,530		$	12.65
Granted		4,242,000		$	35.73
Exercised		(1,822,578	)	$	7.13
Cancelled/forfeited		(806,876	)	$	28.33

Outstanding at December 31, 2015		9,543,076		$	22.64		7.55	$	130,308

Vested and expected to vest at December 31, 2015		8,878,145		$	21.87		7.48	$	127,714

Exercisable at December 31, 2015		4,053,885		$	10.41		5.77	$	102,509

The aggregate intrinsic value of options exercisable as of December 31, 2015 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 $35.65. The aggregate intrinsic value of options exercised during the years ended December 31, 2015, 2014, and 2013 was approximately $55.9 million, $30.6 million, and $20.7 million, respectively, determined as of the date of exercise. The Company received $13.0 million in cash from options exercised during the year ended December 31, 2015.

The weighted average fair value of options granted during the years ended December 31, 2015, 2014, and 2013 was approximately $25.80, $18.90, and $12.66, respectively. As of December 31, 2015, total unrecognized compensation cost related to stock options and purchase rights was approximately $93.5 million, and the weighted average period over which this cost is expected to be recognized is approximately 3.0 years.

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 10 years, which ended with the meeting in 2014. Through December 31, 2015, a total of 1,525,000 shares of common stock had been reserved for issuance under the Purchase Plan. At December 31, 2015, 316,696 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, 2015, 2014, and 2013, a total of 68,793, 97,911, and 122,853 shares of common stock were issued under the Purchase Plan at average prices of $22.62, $6.78, and $2.92, respectively. The weighted average fair value of purchase rights granted during the years ended December 31, 2015, 2014, and 2013 was $14.31, $11.09, and $10.96, respectively. During the years ended December 31, 2015, 2014, and 2013, the Company recorded cash received from the exercise of purchase rights of $1.6 million, $664,000, and $358,000, respectively.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2015
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 $993,000, $489,000, and $240,000 for the years ended December 31, 2015, 2014, and 2013, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

Domestic and foreign pre-tax income (loss) is as follows (in thousands):


	Years Ended December 31,
	2015			2014			2013
Domestic	$	25,854		$	(92,447	)	$	(37,938	)
Foreign		(189,967	)		(28	)		(10	)

	$	(164,113	)	$	(92,475	)	$	(37,948	)

At December 31, 2015, the Company had federal, state, and foreign net operating loss (“NOL”) carryforwards of approximately $449.9 million, $413.8 million, and $187.9 million, respectively. For the year ended December 31, 2015, the Company recognized a state income tax provision of $330,000. This tax liability was associated with California state alternative minimum tax obligations and the apportionment of income to certain state jurisdictions in which the Company did not have corresponding NOLs. No similar state income tax provision was recognized for the years ended December 31, 2014 and 2013. Utilization of the domestic 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, 2015 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 $2.3 million and $36.3 million will expire in 2018 and 2016, respectively, unless utilized. The remaining federal and state NOL carryforwards will begin to expire in 2019 and 2017, respectively. At December 31, 2015, the Company had $12.3 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, 2015, the Company had $8.1 million of state R&D credit carryforwards that have no expiration date. At December 31, 2015, the Company had foreign NOL carryforwards of approximately $184.6 million that will expire in 2022 and $3.3 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 $79.9 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):


	December 31,
	2015			2014
NOL carryforwards	$	161,277		$	168,778
R&D credit carryforwards		17,624			13,668
Capitalized R&D		4,901			6,548
Stock-based compensation		15,260			6,630
Other		2,126			1,615

		201,188			197,239
Valuation allowance		(201,188	)		(197,239	)

	$	—		$	—

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 approximately $3.9 million in 2015 primarily due to an increase in deferred tax assets generated from net operating losses, R&D credits and stock-based compensation expense, partially offset by the expiration of NOL carryforwards in 2015.

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):


	Years Ended December 31,
	2015			2014			2013
Amounts computed at statutory federal rate	$	(55,799	)	$	(31,441	)	$	(12,902	)
Stock-based compensation and other permanent differences		1,752			1,417			244
Reduction of deferred tax assets under Section 382 of the Code		—			—			2,781
R&D credits		(3,782	)		(2,420	)		(1,269	)
Change in valuation allowance		4,580			37,106			13,509
State taxes		742			(5,092	)		(2,140	)
Contingencies		2,247			—			—
Foreign rate differential		48,456			4			—
Other		2,134			426			(223	)

Income tax expense	$	330		$	—		$	—

The tax years 1998-2014 remain open to examination by the major taxing jurisdictions to which the Company is subject.

The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination. For the year ended December 31, 2015, the Company recorded an uncertain tax position reserve of $2.3 million. No similar reserve was recorded for the years ended December 31, 2014 and 2013. Due to the valuation allowance recorded against the Company’s deferred tax assets, none of the total unrecognized tax benefits as of December 31, 2015 would reduce the annual effective tax rate if recognized. The Company does not anticipate that the amount of unrecognized tax benefits as of December 31, 2015 will significantly change within the next twelve months. The Company’s practice is to recognize interest and/or penalties related to uncertain income tax positions in income tax expense. The Company had no interest and/or penalties accrued on the Company’s consolidated balance sheets at December 31, 2015 and 2014, and the Company did not recognize any interest and/or penalties in the statement of operations for the years ended December 31, 2015, 2014 and 2013 related to uncertain tax positions.

The following table provides a reconciliation of changes in unrecognized tax benefits (in thousands):


	Years Ended December 31,
	2015		2014		2013
Balance at beginning of period	$	—	$	—	$	—
Additions related to current period tax positions		2,301		—		—
Additions related to prior period tax positions		—		—		—
Reductions related to prior period tax positions		—		—		—
Reductions related to lapse of statute of limitations		—		—		—

Balance at end of period	$	2,301	$	—	$	—

Commitments and Contingencies

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

Leases and Other Long-Term Commitments

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. Rent expense for operating leases is recorded on a straight-line basis over the life of the lease term. If an operating lease contains 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 $2.9 million, $1.2 million, and $594,000, for the years ended December 31, 2015, 2014, and 2013, respectively.

In 2015, the Company entered into a master lease agreement giving the Company the ability to lease vehicles under operating leases with initial terms of 36 months from the date of delivery. In connection with this lease agreement, the Company established a letter of credit for $375,000, which has automatic annual extensions and is fully secured by restricted cash.

The Company also enters into certain other long-term commitments for goods and services that are outstanding for periods greater than one year. To the extent these long-term commitments are noncancelable, they are reflected in the table below.

Estimated annual future minimum payments related to the Company’s operating leases and other long-term contractual obligations were as follows at December 31, 2015 (in thousands):


2016	$	3,144
2017		2,669
2018		2,419
2019		354
2020		—
Thereafter		—

	$	8,586

The Company also enters into short-term agreements with various vendors and suppliers of goods and services in the normal course of operations through purchase orders or other documentation, or that are undocumented except for an invoice. Such short-term agreements are generally outstanding for periods less than a year and are settled by cash payments upon delivery of goods and services. The nature of the work being conducted under these agreements is such that, in most cases, the services may be stopped on short notice. In such event, the Company would not be liable for the full amount of the agreement and are therefore not reflected in the above table.

Contingent Regulatory Milestone Payment

In connection with the Company’s 2006 license agreement with the Ipsen Group, pursuant to which the Company licensed certain intellectual property rights that complement its patent portfolio for its serotonin platform, including NUPLAZID, the Company made a one-time milestone payment of $2.5 million in the fourth quarter of 2015, adjusted for credits for prior payments made by the Company to Ipsen, upon the U.S. Food and Drug Administration’s (“FDA”) acceptance for filing of the Company’s New Drug Application (“NDA”) for NUPLAZID. This milestone payment of $2.5 million was recognized as license fees in the Company’s statement of operations for the year ended December 31, 2015. The Company may be obligated in a future period to make an additional one-time regulatory milestone payment of $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.

Legal Proceedings

In March 2015, following the Company’s announcement of the update to the timing of its planned NDA submission to the FDA for NUPLAZID for the treatment of Parkinson’s disease psychosis (“PDP”) and the subsequent decline of the price of its common stock, two putative securities class action complaints (captioned Rihn v. ACADIA Pharmaceuticals Inc., Case No. 15-cv-0575-BTM-DHB, and Wright v. ACADIA Pharmaceuticals Inc., Case No. 15-cv-0593- BTM-DHB) were filed in the U.S. District Court for the Southern District of California (the “Court”) against the Company and certain of its current and former officers. The complaints generally alleged that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by making materially false and misleading statements regarding the timing of the Company’s planned NDA submission to the FDA for NUPLAZID, thereby artificially inflating the price of its common stock. The complaints sought unspecified monetary damages and other relief. On April 10 and June 1, 2015, the Court entered orders deferring the defendants’ response to the Rihn and Wright complaints until after the Court appointed a lead plaintiff and assigned lead counsel. On May 12, 2015, several putative stockholders filed separate motions to consolidate the two actions and be appointed lead plaintiff. On September 8, 2015, the Court issued an order consolidating the two actions, appointing lead plaintiff, and assigning lead counsel. On November 16, 2015, lead plaintiff filed a consolidated complaint with the Court which, like the prior complaints, accuses the defendants of making materially false and misleading statements regarding the anticipated timing of the Company’s planned NDA submission to the FDA for NUPLAZID. On January 15, 2016, the defendants filed a motion to dismiss the consolidated complaint. Subject to court approval, the parties stipulated that plaintiffs shall file their opposition to defendants’ motion to dismiss on March 22, 2016 and that defendants shall file their reply to plaintiffs’ opposition on April 21, 2016. The hearing on the defendants’ motion to dismiss is scheduled for May 20, 2016. The Company has assessed such legal proceedings, and given the unpredictability inherent in litigation, the Company cannot predict the outcome of these matters. At this time, the Company is unable to estimate possible losses or ranges of losses that may result from such legal proceedings, and it has not accrued any amounts in connection with such legal proceedings other than ongoing attorneys’ fees.

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event In January 2016, the Company raised net proceeds of approximately $281.6 million from the sale of 10,344,827 shares of its common stock in a follow-on public offering. The common stock issued in this financing is not included in basic or diluted common shares outstanding as of December 31, 2015. In connection with the January 2016 offering, the Company entered into a registration rights agreement (the “Registration Rights Agreement”) with 667, L.P., Baker Brothers Life Sciences, L.P. and 14159, L.P. (the “Baker Entities”), all of which are existing stockholders of the Company and are affiliated with two of its directors, Julian C. Baker and Dr. Stephen R. Biggar. Under the Registration Rights Agreement, the Company agreed that, if at any time and from time to time after April 5, 2016, the Baker Entities demand that the Company register their shares of its common stock, par value $0.0001 per share, for resale under the Securities Act of 1933, as amended (the “Securities Act”), the Company would be obligated to effect such registration. The Company’s registration obligations under the Registration Rights Agreement cover all shares of its common stock now held or later acquired by the Baker Entities (including approximately $75.0 million of shares that the Baker Entities purchased at the public offering price in the January 2016 offering), will continue in effect for up to 10 years, and include the Company’s obligation to facilitate certain underwritten public offerings of its common stock by the Baker Entities in the future. The Company has agreed to bear all expenses incurred by it in effecting any registration pursuant to the Registration Rights Agreement as well as the legal expenses of the Baker Entities of up to $50,000 per underwritten public offering effected pursuant to the Registration Rights Agreement.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

12. 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, 2015 and 2014 are as follows (in thousands, except per share data):


	Fiscal Year 2015 Quarters
	1st			2nd			3rd			4th			Total
Revenues	$	4		$	1		$	39		$	17		$	61
Net loss	$	(40,375	)	$	(39,378	)	$	(38,906	)	$	(45,784	)	$	(164,443	)
Basic and diluted net loss per share(1)	$	(0.40	)	$	(0.39	)	$	(0.39	)	$	(0.45	)	$	(1.63	)

	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	)

(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 Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2015

Accounting Policies [Abstract]

Principles of Consolidation

Principles of Consolidation

Use of Estimates

Use of Estimates

Cash and Cash Equivalents

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity date at the date of purchase of three months or less to be cash equivalents.

Investment Securities

Investment Securities

Fair Value of Financial Instruments

Fair Value of Financial 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:

Property and Equipment

Property and Equipment

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

License Fees

License Fees

Research and Development Expenses

Research and Development Expenses

Concentrations of Risk

Concentrations of Risk

Stock-Based Compensation

Stock-Based Compensation


	Years Ended December 31,
	2015			2014			2013
Stock Options:
Expected volatility		89	%		93	%		94	%
Risk-free interest rate		1-2	%		1-2	%		1-2	%
Expected dividend yield		0	%		0	%		0	%
Expected life of options in years		5.7			5.7			6.0

	Years Ended December 31,
	2015			2014			2013
Employee Stock Purchase Plan:
Expected volatility		51-59	%		44-95	%		69-118	%
Risk-free interest rate		0.1-0.9	%		0.1-0.5	%		0.1-0.3	%
Expected dividend yield		0	%		0	%		0	%
Expected life 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.

Expected Dividend Yield. The Company has never paid any dividends and currently has no plans to do so.

The table below summarizes the total stock-based compensation expense included in the Company’s statements of operations for the periods presented (in thousands):


	Years Ended December 31,
	2015		2014		2013
Research and development	$	12,171	$	5,191	$	2,208
General and administrative		28,023		10,848		3,503

	$	40,194	$	16,039	$	5,711

Income Taxes

Income Taxes

Net Loss Per Share

Net Loss Per Share

Segment Reporting

Segment Reporting

Recently Issued Accounting Standards

Recently Issued Accounting Standards

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

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,
	2015			2014			2013
Stock Options:
Expected volatility		89	%		93	%		94	%
Risk-free interest rate		1-2	%		1-2	%		1-2	%
Expected dividend yield		0	%		0	%		0	%
Expected life of options in years		5.7			5.7			6.0

Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan Rights

	Years Ended December 31,
	2015			2014			2013
Employee Stock Purchase Plan:
Expected volatility		51-59	%		44-95	%		69-118	%
Risk-free interest rate		0.1-0.9	%		0.1-0.5	%		0.1-0.3	%
Expected dividend yield		0	%		0	%		0	%
Expected life in years		0.5-2.0			0.5-2.0			0.5-2.0

Summary of Stock-based Compensation Expense Included in Statements of Operations

The table below summarizes the total stock-based compensation expense included in the Company’s statements of operations for the periods presented (in thousands):


	Years Ended December 31,
	2015		2014		2013
Research and development	$	12,171	$	5,191	$	2,208
General and administrative		28,023		10,848		3,503

	$	40,194	$	16,039	$	5,711

Investment Securities (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
U.S. Treasury notes	$	9,000	$	—	$	(1	)	$	8,999
Government sponsored enterprise securities		103,996		12		(13	)		103,995

	$	112,996	$	12	$	(14	)	$	112,994


	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated 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

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	46,437	$	46,437	$	—	$	—
U.S. Treasury notes		8,999		8,999		—		—
Government sponsored enterprise securities		157,623		—		157,623		—

	$	213,059	$	55,436	$	157,623	$	—


			Fair Value Measurements at Reporting Date Using
	December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	48,423	$	48,423	$	—	$	—
U.S. Treasury notes		2,750		2,750		—		—
Government sponsored enterprise securities		110,235		—		110,235		—
Corporate debt securities		137,648		—		137,648		—
Commercial paper		22,999		—		22,999		—

	$	322,055	$	51,173	$	270,882	$	—

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Property and Equipment, Net

Property and equipment, net, consisted of the following (in thousands):


	December 31,
	2015			2014
Machinery and equipment	$	1,017		$	896
Computers and software		1,336			862
Leasehold improvements		1,413			627
Furniture and fixtures		724			244
Construction-in-process		500			64

		4,990			2,693
Accumulated depreciation		(2,787	)		(2,140	)

	$	2,203		$	553

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):


	December 31,
	2015		2014
Accrued research and development services	$	8,805	$	7,814
Accrued compensation and benefits		5,722		4,167
Accrued consulting and professional fees		4,508		1,497
Other		1,195		340

	$	20,230	$	13,818

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Equity [Abstract]

Stock Option Transactions

Stock option transactions during the year ended December 31, 2015 are presented below:


	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2014		7,930,530		$	12.65
Granted		4,242,000		$	35.73
Exercised		(1,822,578	)	$	7.13
Cancelled/forfeited		(806,876	)	$	28.33

Outstanding at December 31, 2015		9,543,076		$	22.64		7.55	$	130,308

Vested and expected to vest at December 31, 2015		8,878,145		$	21.87		7.48	$	127,714

Exercisable at December 31, 2015		4,053,885		$	10.41		5.77	$	102,509

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Summary of Domestic and Foreign Pre-tax Income (Loss)

Domestic and foreign pre-tax income (loss) is as follows (in thousands):


	Years Ended December 31,
	2015			2014			2013
Domestic	$	25,854		$	(92,447	)	$	(37,938	)
Foreign		(189,967	)		(28	)		(10	)

	$	(164,113	)	$	(92,475	)	$	(37,948	)

Components of Deferred Tax Assets

The components of the deferred tax assets are as follows (in thousands):


	December 31,
	2015			2014
NOL carryforwards	$	161,277		$	168,778
R&D credit carryforwards		17,624			13,668
Capitalized R&D		4,901			6,548
Stock-based compensation		15,260			6,630
Other		2,126			1,615

		201,188			197,239
Valuation allowance		(201,188	)		(197,239	)

	$	—		$	—

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):


	Years Ended December 31,
	2015			2014			2013
Amounts computed at statutory federal rate	$	(55,799	)	$	(31,441	)	$	(12,902	)
Stock-based compensation and other permanent differences		1,752			1,417			244
Reduction of deferred tax assets under Section 382 of the Code		—			—			2,781
R&D credits		(3,782	)		(2,420	)		(1,269	)
Change in valuation allowance		4,580			37,106			13,509
State taxes		742			(5,092	)		(2,140	)
Contingencies		2,247			—			—
Foreign rate differential		48,456			4			—
Other		2,134			426			(223	)

Income tax expense	$	330		$	—		$	—

Unrecognized Tax Benefits

The following table provides a reconciliation of changes in unrecognized tax benefits (in thousands):


	Years Ended December 31,
	2015		2014		2013
Balance at beginning of period	$	—	$	—	$	—
Additions related to current period tax positions		2,301		—		—
Additions related to prior period tax positions		—		—		—
Reductions related to prior period tax positions		—		—		—
Reductions related to lapse of statute of limitations		—		—		—

Balance at end of period	$	2,301	$	—	$	—

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Estimated Annual Future Minimum Payments under Operating Leases and other Long-term Contractual Obligations

Estimated annual future minimum payments related to the Company’s operating leases and other long-term contractual obligations were as follows at December 31, 2015 (in thousands):


2016	$	3,144
2017		2,669
2018		2,419
2019		354
2020		—
Thereafter		—

	$	8,586

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data


	Fiscal Year 2015 Quarters
	1st			2nd			3rd			4th			Total
Revenues	$	4		$	1		$	39		$	17		$	61
Net loss	$	(40,375	)	$	(39,378	)	$	(38,906	)	$	(45,784	)	$	(164,443	)
Basic and diluted net loss per share(1)	$	(0.40	)	$	(0.39	)	$	(0.39	)	$	(0.45	)	$	(1.63	)

	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	)

(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 Accounting Policies - Schedule of Estimated Useful Lives by Major Asset Category (Detail)	12 Months Ended
	Dec. 31, 2015
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 Accounting Policies - Additional Information (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) Segment shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares
Summary Of Significant Accounting Policy [Line Items]
Impairment losses	$ 0
Stock compensation expense related to non-employee stock options	$ 40,194,000	$ 16,039,000	$ 5,711,000
Antidilutive securities to purchase common stock \| shares	11,525,000	9,902,000	9,314,000
Number of business segments \| Segment	1
Chief Executive Officer [Member]
Summary Of Significant Accounting Policy [Line Items]
Stock compensation expense related to non-employee stock options	$ 9,000,000
Non Employee Stock [Member]
Summary Of Significant Accounting Policy [Line Items]
Stock compensation expense related to non-employee stock options			$ 584,000
Performance-based Stock Options
Summary Of Significant Accounting Policy [Line Items]
Stock compensation expense related to non-employee stock options	$ 0

Assumptions Used to Estimate Fair Value of Employee Stock Options (Detail) - Stock Options	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assumptions used to Determine Fair Value Options [Line Items]
Expected volatility	89.00%	93.00%	94.00%
Risk-free interest rate, minimum	1.00%	1.00%	1.00%
Risk-free interest rate, maximum	2.00%	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	5 years 8 months 12 days	6 years

Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan Rights (Detail) - Employee Stock Purchase Plan	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Purchase Plan [Line Items]
Expected volatility, minimum	51.00%	44.00%	69.00%
Expected volatility, maximum	59.00%	95.00%	118.00%
Risk-free interest rate, minimum	0.10%	0.10%	0.10%
Risk-free interest rate, maximum	0.90%	0.50%	0.30%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Employee Stock Purchase Plan [Line Items]
Expected life in years	6 months	6 months	6 months
Maximum
Employee Stock Purchase Plan [Line Items]
Expected life in years	2 years	2 years	2 years

Summary of Significant Accounting Policies - Summary of Stock-based Compensation Expense Included in Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 40,194	$ 16,039	$ 5,711
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	12,171	5,191	2,208
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 28,023	$ 10,848	$ 3,503

Investment Securities, All Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 112,996	$ 260,647
Unrealized Gains	12	32
Unrealized Losses	(14)	(47)
Estimated Fair Value	112,994	260,632
U.S. Treasury notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,000	2,748
Unrealized Gains		2
Unrealized Losses	(1)
Estimated Fair Value	8,999	2,750
Government sponsored enterprise securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	103,996	97,237
Unrealized Gains	12	8
Unrealized Losses	(13)	(10)
Estimated Fair Value	$ 103,995	97,235
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		137,682
Unrealized Gains		3
Unrealized Losses		(37)
Estimated Fair Value		137,648
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		22,980
Unrealized Gains		19
Estimated Fair Value		$ 22,999

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Investment, fair value disclosure	$ 213,059	$ 322,055

Fair Value Measurements of Cash Equivalents and Available-For-Sale Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	$ 112,994	$ 260,632
Investments, fair value disclosure	213,059	322,055
Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value disclosure	46,437	48,423
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	8,999	2,750
Government sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	157,623	110,235
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
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
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	55,436	51,173
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	46,437	48,423
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	8,999	2,750
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	157,623	270,882
Significant Other Observable Inputs (Level 2) \| Government sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	$ 157,623	110,235
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
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

Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,990	$ 2,693
Accumulated depreciation	(2,787)	(2,140)
Property and equipment, net	2,203	553
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,017	896
Computers and Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,336	862
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,413	627
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	724	244
Construction-in-Process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 500	$ 64

Balance Sheet Components - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation of property and equipment	$ 647,000	$ 206,000	$ 79,000
Removal of fully depreciated property, machinery and equipment	$ 72,000	$ 40,000	$ 2,800,000

Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued research and development services	$ 8,805	$ 7,814
Accrued compensation and benefits	5,722	4,167
Accrued consulting and professional fees	4,508	1,497
Other	1,195	340
Accrued liabilities	$ 20,230	$ 13,818

Collaborative Research Agreements - Additional Information (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) Contract	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenues	$ 17	$ 39	$ 1	$ 4	$ 47	$ 15	$ 28	$ 30	$ 61	$ 120	$ 1,145
Allergan, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total number of collaboration agreements \| Contract									3
Collaborative revenues									$ 61	$ 40	$ 571
Allergan, Inc. \| 2003 Research Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, original research term									3 years
Collaboration agreement, beginning date									2003
Allergan, Inc. \| Chronic Pain Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, estimated development and regulatory milestones	$ 10,000								$ 10,000

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Jun. 30, 2015	Mar. 31, 2014	May 31, 2013	Dec. 31, 2012	Jan. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Class of Stock [Line Items]
Common stock, shares authorized	225,000,000					225,000,000	150,000,000
Net proceeds from sale of common stock		$ 196,800	$ 107,900			$ 14,547	$ 203,851	$ 111,682
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	$ 13,900
Common stock sale price per share				$ 4.43	$ 1.19375
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	$ 3,300
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%
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						$ 35.65
Aggregate intrinsic value of stock options exercised						$ 55,900	$ 30,600	$ 20,700
Cash received from options exercised						$ 13,000
Weighted average fair value of options granted						$ 25.80	$ 18.90	$ 12.66
Unrecognized compensation costs						$ 93,500
Weighted average period cost expected to be recognized						3 years
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						68,793	97,911	122,853
Average price of stock issued under purchase plan						$ 22.62	$ 6.78	$ 2.92
Issuance of common stock pursuant to employee stock purchase plan						$ 1,556	$ 664	$ 358
Expire on December 17, 2019
Class of Stock [Line Items]
Warrant expiration date						Dec. 17, 2019
Expire on January 11, 2018
Class of Stock [Line Items]
Warrant expiration date						Jan. 11, 2018
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock reserved for issuance under stock purchase plan						1,525,000
Term of ESPP Evergreen Provision						10 years
Common stock remained available for issuance pursuant to the Purchase Plan						316,696
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						$ 14.31	$ 11.09	$ 10.96
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						15,738,857
Common stock available for grants						6,195,781
Common stock reserved for issuance under stock purchase plan	5,000,000
Over-Allotment Option
Class of Stock [Line Items]
Share of common stock issued		960,000	1,200,000

Stock Option Transactions (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Number of Shares
Option Outstanding, Beginning Balance \| shares	7,930,530
Granted \| shares	4,242,000
Exercised \| shares	(1,822,578)
Cancelled/forfeited \| shares	(806,876)
Option Outstanding, Ending Balance \| shares	9,543,076
Vested and expected to vest \| shares	8,878,145
Exercisable \| shares	4,053,885
Weighted Average Exercise Prices
Weighted Average Exercise Prices, Beginning Balance \| $ / shares	$ 12.65
Weighted Average Exercise Prices, granted \| $ / shares	35.73
Weighted Average Exercise Prices, exercised \| $ / shares	7.13
Weighted Average Exercise Prices, Cancelled/forfeited \| $ / shares	28.33
Weighted Average Exercise Prices, Ending Balance \| $ / shares	22.64
Weighted Average Exercise Prices, Vested and expected to vest \| $ / shares	21.87
Weighted Average Exercise Prices, Exercisable \| $ / shares	$ 10.41
Weighted average remaining contractual term, outstanding	7 years 6 months 18 days
Weighted average remaining contractual term, Vested and expected to vest	7 years 5 months 23 days
Weighted average remaining contractual term, Exercisable	5 years 9 months 7 days
Aggregate Intrinsic Value, Outstanding \| $	$ 130,308
Aggregate Intrinsic Value, Vested and expected to vest \| $	127,714
Aggregate Intrinsic Value, Exercisable \| $	$ 102,509

401 (k) Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	$ 993,000	$ 489,000	$ 240,000

Income Taxes - Summary of Domestic and Foreign Pre-tax Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
Domestic pre-tax income (loss)	$ 25,854	$ (92,447)	$ (37,938)
Foreign pre-tax income (loss)	(189,967)	(28)	(10)
Total pre-tax income (loss)	$ (164,113)	$ (92,475)	$ (37,948)

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
State income tax provision	$ 330,000	$ 0	$ 0
Federal R&D credit carryforwards	12,300,000
Net operating loss carryforwards related to excess tax deductions for stock compensation	79,900,000
Increase in valuation allowance of deferred tax assets	3,900,000
Unrecognized tax reserves	2,301,000	0	0
Total unrecognized tax benefits that would reduce the annual effective tax rate if recognized	0
Interest and/or penalties accrued	0	0
Interest and/or penalties	0	$ 0	$ 0
Federal
Income Tax [Line Items]
Operating loss carryforwards	$ 449,900,000
Remaining net operating loss carryforward, expiration year	2019
Federal \| Expiring in 2018
Income Tax [Line Items]
Operating loss carryforwards	$ 2,300,000
State
Income Tax [Line Items]
Operating loss carryforwards	$ 413,800,000
Remaining net operating loss carryforward, expiration year	2017
Net operating loss carryforwards with no expiration date	$ 8,100,000
State \| Expiring in 2015
Income Tax [Line Items]
Operating loss carryforwards	36,300,000
Foreign
Income Tax [Line Items]
Operating loss carryforwards	187,900,000
Net operating loss carryforwards with no expiration date	3,300,000
Foreign \| Operating Loss Carryforwards Expiring 2022
Income Tax [Line Items]
Operating loss carryforwards	184,600,000
Expire in 2018
Income Tax [Line Items]
Federal R&D credit carryforwards	$ 119,000

Income Taxes - Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
NOL carryforwards	$ 161,277	$ 168,778
R&D credit carryforwards	17,624	13,668
Capitalized R&D	4,901	6,548
Stock-based compensation	15,260	6,630
Other	2,126	1,615
Deferred Tax Assets, Gross	201,188	197,239
Valuation allowance	(201,188)	(197,239)
Deferred Tax Assets, Net	$ 0	$ 0

Income Taxes - Reconciliation of Income Taxes to Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Amounts computed at statutory federal rate	$ (55,799)	$ (31,441)	$ (12,902)
Stock-based compensation and other permanent differences	1,752	1,417	244
Reduction of deferred tax assets under Section 382 of the Code			2,781
R&D credits	(3,782)	(2,420)	(1,269)
Change in valuation allowance	4,580	37,106	13,509
State taxes	742	(5,092)	(2,140)
Contingencies	2,247
Foreign rate differential	48,456	4
Other	2,134	$ 426	$ (223)
Income tax expense	$ 330

Income Taxes - Unrecognized Tax Benefits (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 0	$ 0
Additions related to current period tax positions	2,301,000
Additions related to prior period tax positions	0	0	$ 0
Reductions related to prior period tax positions	0	0	0
Reductions related to lapse of statute of limitations	0	0	0
Balance at end of period	$ 2,301,000	$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Commitments [Line Items]
Operating lease, expiration year	2019-02
Rent expense	$ 2,900,000	$ 1,200,000	$ 594,000.0
One-time regulatory milestone payment pursuant to agreement with Ipsen Group	2,500,000
Letter of Credit [Member]
Other Commitments [Line Items]
Letter of credit	$ 375,000
Vehicles [Member]
Other Commitments [Line Items]
Operating leases arrangement term	36 months
Payable upon filing of first regulatory application with FDA
Other Commitments [Line Items]
One-time regulatory milestone payment pursuant 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 payment pursuant to agreement with Ipsen Group	$ 8,000,000
Maximum
Other Commitments [Line Items]
Percentage of royalty payments obligation on net product sales	2.00%

Commitments and Contingencies - Estimated Annual Future Minimum Payments under Operating Leases and other Long-term Contractual Obligations (Detail) $ in Thousands	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2016	$ 3,144
2017	2,669
2018	2,419
2019	354
2020	0
Thereafter	0
Operating Leases, Future Minimum Payments Due, Total	$ 8,586

Subsequent Event - Additional Information (Detail) - USD ($)	1 Months Ended					12 Months Ended
	Jan. 31, 2016	Mar. 31, 2014	May 31, 2013	Dec. 31, 2012	Jan. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Net proceeds from sale of common stock		$ 196,800,000	$ 107,900,000			$ 14,547,000	$ 203,851,000	$ 111,682,000
Share of common stock issued		7,360,000	9,200,000	19,000,000	12,565,446
Common stock, par value						$ 0.0001	$ 0.0001
Value of shares purchased by Baker Entities in January 2016 public offering						$ 10,000	$ 10,000
Subsequent Event
Subsequent Event [Line Items]
Net proceeds from sale of common stock	$ 281,600,000
Share of common stock issued	10,344,827
Subsequent Event \| Registration Rights Agreement
Subsequent Event [Line Items]
Common stock, par value	$ 0.0001
Expiration period	10 years
Maximum amount of expense agreed to bear under the agreement	$ 50,000
Subsequent Event \| Registration Rights Agreement \| Baker Brothers Life Sciences L.P.
Subsequent Event [Line Items]
Value of shares purchased by Baker Entities in January 2016 public offering	$ 75,000,000

Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Revenues

$ 17

$ 39

$ 1

$ 4

$ 47

$ 15

$ 28

$ 30

$ 61

$ 120

$ 1,145

Net loss

$ (45,784)

$ (38,906)

$ (39,378)

$ (40,375)

$ (28,366)

$ (24,786)

$ (21,495)

$ (17,828)

$ (164,443)

$ (92,475)

$ (37,948)

Basic and diluted net loss per share

$ (0.45)

^[1]

$ (0.39)

^[1]

$ (0.39)

^[1]

$ (0.40)

^[1]

$ (0.28)

^[1]

$ (0.25)

^[1]

$ (0.22)

^[1]

$ (0.19)

^[1]

$ (1.63)

^[1]

$ (0.95)

^[1]

$ (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.

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details