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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2013	Jul. 31, 2013
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Trading Symbol	ACAD
Entity Registrant Name	ACADIA PHARMACEUTICALS INC
Entity Central Index Key	0001070494
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		88,783,766

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands

Jun. 30, 2013

Dec. 31, 2012

^[1]

Assets

Cash and cash equivalents

$ 24,247

$ 57,899

Investment securities, available-for-sale

181,204

50,068

Prepaid expenses, receivables and other current assets

1,310

581

Total current assets

206,761

108,548

Property and equipment, net

Other assets

Total assets

206,909

108,590

Liabilities, redeemable common stock and stockholders' equity

Accounts payable

1,177

1,375

Accrued expenses

6,488

4,139

Deferred revenue

111

434

Total current liabilities

7,776

5,948

Commitments and contingencies (Note 9)

Redeemable common stock, $0.0001 par value; 5,347,137 shares issued and outstanding at June 30, 2013 and December 31, 2012 (Note 9)

17,658

Stockholders' equity

Preferred stock, $0.0001 par value; 5,000,000 shares authorized at June 30, 2013 and December 31, 2012; no shares issued and outstanding at June 30, 2013 and December 31, 2012

Common stock, $0.0001 par value; 150,000,000 shares authorized at June 30, 2013 and December 31, 2012; 83429819 shares and 73,334,216 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively

Additional paid-in capital

564,417

452,693

Accumulated deficit

(382,924)

(367,720)

Accumulated other comprehensive income (loss)

(26)

Total stockholders' equity

181,475

84,984

Total liabilities, redeemable common stock and stockholders' equity

$ 206,909

$ 108,590

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares

Jun. 30, 2013

Dec. 31, 2012

^[1]

Statement Of Financial Position [Abstract]

Redeemable common stock, par value

$ 0.0001

Redeemable common stock, shares issued

5,347,137

Redeemable common stock, shares outstanding

5,347,137

Preferred stock, par value

$ 0.0001

Preferred stock, shares authorized

5,000,000

Preferred stock, shares issued

Preferred stock, shares outstanding

Common stock, par value

$ 0.0001

Common stock, shares authorized

150,000,000

Common stock, shares issued

83,429,819

73,334,216

Common stock, shares outstanding

83,429,819

73,334,216

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues
Collaborative revenues	$ 451	$ 599	$ 868	$ 1,049
Operating expenses
Research and development (includes stock-based compensation of $473, $154, $727, and $293, respectively)	7,112	4,472	11,542	9,493
General and administrative (includes stock-based compensation of $591, $324, $919, and $598, respectively)	2,496	1,556	4,647	3,216
Total operating expenses	9,608	6,028	16,189	12,709
Loss from operations	(9,157)	(5,429)	(15,321)	(11,660)
Interest income, net	76	10	117	23
Net loss	$ (9,081)	$ (5,419)	$ (15,204)	$ (11,637)
Net loss per common share, basic and diluted	$ (0.11)	$ (0.10)	$ (0.19)	$ (0.22)
Weighted average common shares outstanding, basic and diluted	83,410	52,961	81,105	52,932

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Research and development
Stock-based compensation	$ 473	$ 154	$ 727	$ 293
General and Administrative
Stock-based compensation	$ 591	$ 324	$ 919	$ 598

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (9,081)	$ (5,419)	$ (15,204)	$ (11,637)
Other comprehensive loss:
Unrealized loss on investment securities	(41)	(3)	(30)	(6)
Comprehensive loss	$ (9,122)	$ (5,422)	$ (15,234)	$ (11,643)

- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6518256

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-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

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+ Details

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Cash flows from operating activities

Net loss

$ (15,204)

$ (11,637)

Adjustments to reconcile net loss to net cash used in operating activities:

Stock-based compensation

1,646

891

Amortization of investment premium

473

(156)

Other

(44)

Changes in operating assets and liabilities:

Prepaid expenses, receivables and other current assets

(729)

475

Other assets

(56)

Accounts payable

(198)

(1,203)

Accrued expenses

2,349

1,721

Deferred revenue

(323)

(85)

Net cash used in operating activities

(12,029)

(10,030)

Cash flows from investing activities

Purchases of investment securities

(162,032)

(9,838)

Maturities of investment securities

30,393

22,005

Proceeds from sales (purchases) of property and equipment

(63)

103

Net cash (used in) provided by investing activities

(131,702)

12,270

Cash flows from financing activities

Proceeds from issuance of common stock, net of issuance costs

110,079

Repayments of long-term debt

(19)

Net cash provided by financing activities

110,079

Net (decrease) increase in cash and cash equivalents

(33,652)

2,319

Cash and cash equivalents

Beginning of period

57,899

^[1]

6,889

End of period

$ 24,247

$ 9,208

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2013
Accounting Policies [Abstract]
Basis of Presentation	1. Basis of Presentation The accompanying unaudited condensed consolidated financial statements of ACADIA Pharmaceuticals Inc. should be read in conjunction with the audited financial statements and notes thereto as of and for the year ended December 31, 2012 included in the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (the “SEC”). The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, since they are interim statements, the accompanying financial statements do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, the accompanying financial statements reflect all adjustments (consisting of normal recurring adjustments) that are necessary for a fair statement of the financial position, results of operations and cash flows for the interim periods presented. Interim results are not necessarily indicative of results for a full year. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates. The Company has incurred substantial operating losses since its inception due in large part to expenditures for its research and development activities. As of June 30, 2013, the Company had an accumulated deficit of $382.9 million. The Company expects to continue to incur operating losses for at least the next several years as it pursues the development and commercialization of its product candidates. The Company will require significant additional financing in the future to fund its operations. Future capital requirements will depend on many factors, including the progress in, the outcome of and the costs of the Company’s clinical trials and other development activities, costs associated with establishing necessary sales and marketing capabilities, the scope, prioritization and number of its research and development programs, and the ability of its collaborators and the Company to reach the milestones, and other events or developments under its collaboration and license agreements, and the ability of the Company to enter into new, and to maintain existing, collaboration and license agreements. Until the Company can generate significant continuing revenues, it expects to fund its operations through its existing cash, cash equivalents and investment securities, payments from existing and potential future collaborations, proceeds from private or public sales of its equity securities, debt financing, grant funding, or by licensing all or a portion of its product candidates or technology. The Company cannot be certain that additional funding will be available on acceptable terms, or at all. Conditions in the financial markets and other factors could have a material adverse effect on the Company’s ability to access sufficient funding on acceptable terms, or at all. If the Company cannot raise adequate additional capital, it will be required to delay, further reduce the scope of, or eliminate one or more of its research or development programs or its commercialization efforts. In addition, the Company may be required to relinquish greater, or even all, rights to product candidates at earlier stages of development or on less favorable terms than it would otherwise choose.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

+ References

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+ Details

Earnings (Loss) Per Share

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Earnings (Loss) Per Share

2. Earnings (Loss) Per Share

Basic earnings (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period. For the three and six months ended June 30, 2013, the calculation of the weighted average number of common shares outstanding includes 5.3 million shares of redeemable common stock issued during 2012. Diluted earnings (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding during the period, increased to include potential dilutive common shares that were outstanding during the period. The effect of outstanding stock options and warrants is reflected, when dilutive, in diluted earnings per common share by application of the treasury stock method. The Company has excluded all outstanding stock options and warrants from the calculation of diluted net loss per common share because all such securities are antidilutive for all periods presented.

Shares used in calculating basic and diluted net loss per common share exclude these potential common shares (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
	(unaudited)				(unaudited)
Antidilutive options to purchase common stock		7,217		7,178		7,129		6,721
Antidilutive warrants to purchase common stock		3,725		4,655		3,725		4,667

		10,942		11,833		10,854		11,388

Stock-Based Compensation	6 Months Ended
Stock-Based Compensation	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	3. Stock-Based Compensation The fair value of each stock option and each employee stock purchase plan right granted is estimated on the grant date under the fair value method using the Black-Scholes valuation model. The estimated fair values of the stock options or purchase plan rights, including the effect of estimated forfeitures, are then expensed over the vesting period. The Company recognized stock-based compensation expense of $1.1 million and $1.6 million during the three and six months ended June 30, 2013, respectively, and $478,000 and $891,000 during the three and six months ended June 30, 2012, respectively. At June 30, 2013, total unrecognized compensation cost related to stock options and purchase plan rights was $15.0 million, which is expected to be recognized over a weighted-average period of 2.7 years.

Accrued Expenses

6 Months Ended

Jun. 30, 2013

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Accrued Expenses

4. Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	June 30, 2013		December 31, 2012
	(unaudited)
Accrued clinical and research services	$	5,155	$	3,216
Accrued compensation and benefits		913		413
Accrued professional fees		339		364
Other		81		146

Total	$	6,488	$	4,139

Investment Securities

6 Months Ended

Jun. 30, 2013

Investments Debt And Equity Securities [Abstract]

Investment Securities

5. Investment Securities

Investment securities, including investment securities available-for-sale and investment securities classified as cash equivalents, consisted of the following (in thousands):


	June 30, 2013
	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Estimated Fair Value
	(unaudited)
Government sponsored enterprise securities	$	95,490	$	4	$	(17	)	$	95,477
Commercial paper		40,509		74		—			40,583
Corporate debt securities		61,972		—		(91	)		61,881

	$	197,971	$	78	$	(108	)	$	197,941


	December 31, 2012
	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Estimated Fair Value
U.S. Treasury notes	$	2,029	$	1	$	—		$	2,030
Government sponsored enterprise securities		54,353		4		(5	)		54,352

	$	56,382	$	5	$	(5	)	$	56,382

The Company has classified all of its investment securities available-for-sale, including those with maturities beyond one year, as current assets on the consolidated balance sheets based on the highly liquid nature of the investment securities and because these investment securities are considered available for use in current operations. As of June 30, 2013, the Company held $25.8 million of available-for-sale investment securities with contractual maturity dates more than one year and less than two years, and all other 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

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Fair Value Measurements

6. Fair Value Measurements

As of June 30, 2013, the Company held $204.6 million of cash equivalents and available-for-sale investment securities consisting of a money market fund and high quality, marketable debt instruments of corporations, financial institutions and government sponsored enterprises. The Company has adopted an investment policy and established 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 AA or A1+/p1 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 and the Company’s investment securities classified as Level 2 are valued using other observable inputs such as recent trades for the securities or similar securities, interest rates on similar securities, or yield curves or benchmark interest rates observable at commonly quoted intervals. 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. No other-than-temporary impairments were identified for the investment securities held by the Company as of June 30, 2013 or December 31, 2012.

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
	June 30, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(unaudited)
Money market fund	$	6,692	$	6,692	$	—	$	—
Government sponsored enterprise securities		95,477		—		95,477		—
Commercial paper		40,583		—		40,583		—
Corporate debt securities		61,881		—		61,881		—

	$	204,633	$	6,692	$	197,941	$	—


			Fair Value Measurements at Reporting Date Using
	December 31, 2012		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	51,216	$	51,216	$	—	$	—
U.S. Treasury notes		2,030		2,030		—		—
Government sponsored enterprise securities		54,352		—		54,352		—

	$	107,598	$	53,246	$	54,352	$	—

- 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

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2013
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity 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.

- 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

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-Publisher FASB
-Name Accounting Standards Codification
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-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 Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph d
-Article 4

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Collaborative Research and Licensing Agreements	6 Months Ended
Collaborative Research and Licensing Agreements	Jun. 30, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborative Research and Licensing Agreements	8. Collaborative Research and Licensing Agreements The Company has been a party to three separate collaboration agreements with Allergan, Inc. The March 2003 collaboration originally provided for a three-year research term, which had been extended by the parties through March 2013. Pursuant to this agreement, the Company had received an aggregate of $19.5 million in payments, consisting of an upfront payment, research funding and related fees, through the conclusion of the collaboration in March 2013. The Company’s two other collaboration agreements with Allergan involve the development of product candidates in the areas of glaucoma and chronic pain. Under the glaucoma collaboration, the Company had received an aggregate of $9.9 million in payments as of June 30, 2013, and is eligible to receive up to an aggregate of approximately $15.5 million in additional payments per product upon the achievement of development and regulatory milestones. Under the chronic pain collaboration, the Company had received an aggregate of $10.5 million in payments as of June 30, 2013, and is eligible to receive up to an aggregate of $10 million in additional payments upon the achievement of development and regulatory milestones. The Company also is eligible to receive royalties on future product sales worldwide, if any, under each of the two ongoing collaboration agreements with Allergan. The Company recognized revenues, consisting of research funding, milestone and related fees, from its collaboration agreements with Allergan of $257,000 and $544,000 during the three and six months ended June 30, 2013, respectively, and $285,000 and $548,000 during the three and six months ended June 30, 2012, respectively. In March 2009, the Company entered into a collaboration agreement with Meiji Seika Pharma Co., Ltd. (“Meiji Seika Pharma”). In July 2012, the Company and Meiji Seika Pharma jointly decided to discontinue the development program that was being pursued under the collaboration, and the collaboration agreement was terminated pursuant to its terms. Under the collaboration agreement, the Company had received $3 million in non-refundable license fees as well as payments for the reimbursement of development costs that it had incurred during the collaboration. Payments received from Meiji Seika Pharma were deferred and recognized as revenues using a contingency-adjusted performance model over the estimated period of the Company’s performance. Upon the termination of this collaboration agreement and the end of the Company’s related performance obligations, the Company recorded as revenue all of the remaining deferred revenue from this collaboration during the third quarter of 2012. The Company recognized revenues relating to this collaboration of $109,000 and $222,000 during the three and six months ended June 30, 2012, respectively.

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies The Company has entered into agreements with contract research organizations and other external service providers primarily for services in connection with the development of its product candidates. The Company was contractually obligated for up to approximately $12.3 million of future services under these agreements as of June 30, 2013. The nature of the work being conducted under the Company’s agreements with contract research organizations is such that, in most cases, the services may be stopped with short notice. In such event, the Company would not be liable for the full amount of the contract. The Company’s actual contractual obligations may vary depending upon several factors, including the progress and results of the underlying studies. In March 2012, the Company entered into an At-The-Market Issuance Sales Agreement (“ATM Agreement”) with MLV & Co. LLC. Pursuant to the ATM Agreement, in 2012 the Company sold 5,347,137 shares of common stock. In November 2012, the Company determined that it had failed to timely file a Current Report on Form 8-K to report the election of a new director in January 2012. As a result, the Company became ineligible to use its effective shelf registration statement on Form S-3. Therefore, sales of the Company’s common stock made pursuant to the ATM Agreement in 2012 may be subject to potential rescission rights for an amount up to $17.7 million, the aggregate purchase price paid for such shares, plus statutory interest. No stockholder has claimed or attempted to exercise any rescission rights to date and any such rights expire in the current year. If it were determined that the Company sold unregistered securities, the Company could be subject to enforcement actions or penalties and fines by regulatory authorities. The Company is unable to predict the likelihood of any claims or actions being brought against it or the amount of any potential penalties or fines related to such sales of common stock. These shares are treated as outstanding for financial reporting purposes.

Recent Accounting Pronouncements	6 Months Ended
Recent Accounting Pronouncements	Jun. 30, 2013
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	10. Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board issued authoritative guidance related to reclassifications out of accumulated other comprehensive income (loss). This guidance requires that companies present information about significant items reclassified out of accumulated other comprehensive income (loss) by component either on the face of the financial statements where net income is presented or as a separate disclosure in the footnotes to the financial statements. This authoritative guidance became effective in the current quarter. The Company’s components of accumulated other comprehensive loss include unrealized gains and losses on available-for-sale investment securities and foreign currency translation adjustments. During the three and six months ended June 30, 2013 and 2012, no realized gains or losses on available-for-sale investment securities were recognized and no changes occurred within foreign currency translation adjustments, therefore, no amounts were reclassified out of accumulated other comprehensive loss to net loss for the periods presented. Accordingly, the adoption of this guidance had no impact on the Company’s consolidated financial position, results of operations or cash flows.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6507316

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6510796

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22583-107794

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Indirect Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6515603

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22580-107794

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.10-01.(b)(6))
-URI http://asc.fasb.org/extlink&oid=27015980&loc=d3e46468-122699

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accounting Change
-URI http://asc.fasb.org/extlink&oid=6503790

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22499-107794

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Retrospective Application
-URI http://asc.fasb.org/extlink&oid=6523989

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e765-108305

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e725-108305

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 01
-Paragraph b
-Subparagraph 6
-Article 10

+ Details

Recent Accounting Pronouncements (Policies)	6 Months Ended
Recent Accounting Pronouncements (Policies)	Jun. 30, 2013
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board issued authoritative guidance related to reclassifications out of accumulated other comprehensive income (loss). This guidance requires that companies present information about significant items reclassified out of accumulated other comprehensive income (loss) by component either on the face of the financial statements where net income is presented or as a separate disclosure in the footnotes to the financial statements. This authoritative guidance became effective in the current quarter. The Company’s components of accumulated other comprehensive loss include unrealized gains and losses on available-for-sale investment securities and foreign currency translation adjustments. During the three and six months ended June 30, 2013 and 2012, no realized gains or losses on available-for-sale investment securities were recognized and no changes occurred within foreign currency translation adjustments, therefore, no amounts were reclassified out of accumulated other comprehensive loss to net loss for the periods presented. Accordingly, the adoption of this guidance had no impact on the Company’s consolidated financial position, results of operations or cash flows.

Earnings (Loss) Per Share (Tables)

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Potential Common Shares Excluded in Calculating Basic and Diluted Net Loss Per Common Share

Shares used in calculating basic and diluted net loss per common share exclude these potential common shares (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
	(unaudited)				(unaudited)
Antidilutive options to purchase common stock		7,217		7,178		7,129		6,721
Antidilutive warrants to purchase common stock		3,725		4,655		3,725		4,667

		10,942		11,833		10,854		11,388

Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2013

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	June 30, 2013		December 31, 2012
	(unaudited)
Accrued clinical and research services	$	5,155	$	3,216
Accrued compensation and benefits		913		413
Accrued professional fees		339		364
Other		81		146

Total	$	6,488	$	4,139

Investment Securities (Tables)

6 Months Ended

Jun. 30, 2013

Investments Debt And Equity Securities [Abstract]

Investment Securities, Available-for-Sale and Classified as Cash Equivalents

Investment securities, including investment securities available-for-sale and investment securities classified as cash equivalents, consisted of the following (in thousands):


	June 30, 2013
	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Estimated Fair Value
	(unaudited)
Government sponsored enterprise securities	$	95,490	$	4	$	(17	)	$	95,477
Commercial paper		40,509		74		—			40,583
Corporate debt securities		61,972		—		(91	)		61,881

	$	197,971	$	78	$	(108	)	$	197,941


	December 31, 2012
	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Estimated Fair Value
U.S. Treasury notes	$	2,029	$	1	$	—		$	2,030
Government sponsored enterprise securities		54,353		4		(5	)		54,352

	$	56,382	$	5	$	(5	)	$	56,382

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

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
	June 30, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(unaudited)
Money market fund	$	6,692	$	6,692	$	—	$	—
Government sponsored enterprise securities		95,477		—		95,477		—
Commercial paper		40,583		—		40,583		—
Corporate debt securities		61,881		—		61,881		—

	$	204,633	$	6,692	$	197,941	$	—


			Fair Value Measurements at Reporting Date Using
	December 31, 2012		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market fund	$	51,216	$	51,216	$	—	$	—
U.S. Treasury notes		2,030		2,030		—		—
Government sponsored enterprise securities		54,352		—		54,352		—

	$	107,598	$	53,246	$	54,352	$	—

Basis of Presentation - Additional Information (Detail) - USD ($)
$ in Thousands

Jun. 30, 2013

Dec. 31, 2012

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Accumulated deficit

$ (382,924)

$ (367,720)

^[1]

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Earnings (Loss) Per Share - Additional Information (Detail) - shares

Jun. 30, 2013

Dec. 31, 2012

Earnings Per Share [Abstract]

Redeemable common stock, shares outstanding

5,347,137

^[1]

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Potential Common Shares Excluded in Calculating Basic and Diluted Net Loss Per Common Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	10,942	11,833	10,854	11,388
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	7,217	7,178	7,129	6,721
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities to purchase common stock	3,725	4,655	3,725	4,667

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Compensation expense	$ 1,100	$ 478	$ 1,646	$ 891
Unrecognized compensation costs	$ 15,000		$ 15,000
Weighted-average period to be recognized			2 years 8 months 12 days

Accrued Expenses (Detail) - USD ($)
$ in Thousands

Jun. 30, 2013

Dec. 31, 2012

Payables And Accruals [Abstract]

Accrued clinical and research services

$ 5,155

$ 3,216

Accrued compensation and benefits

913

413

Accrued professional fees

339

364

Other

146

Total

$ 6,488

$ 4,139

^[1]

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Investment Securities, Available-for-Sale and Classified as Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Amortized Cost	$ 197,971	$ 56,382
Unrealized Gains	78	5
Unrealized (Losses)	(108)	(5)
Estimated Fair Value	197,941	56,382
U.S. Treasury notes
Schedule of Investments [Line Items]
Amortized Cost		2,029
Unrealized Gains		1
Estimated Fair Value		2,030
Government sponsored enterprise securities
Schedule of Investments [Line Items]
Amortized Cost	95,490	54,353
Unrealized Gains	4	4
Unrealized (Losses)	(17)	(5)
Estimated Fair Value	95,477	$ 54,352
Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	40,509
Unrealized Gains	74
Estimated Fair Value	40,583
Corporate debt securities
Schedule of Investments [Line Items]
Amortized Cost	61,972
Unrealized (Losses)	(91)
Estimated Fair Value	$ 61,881

- Definition

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12.Column C.3,4)
-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611133-123010

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-12C.Column C.7)
-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611225-123010

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.Column E.2,3)
-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611322-123010

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.Column C.6)
-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611282-123010

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column C
-Article 12

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph 3, 4
-Article 12

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 14
-Paragraph 2, 3
-Article 12

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 13
-Paragraph 6
-Article 12

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12C
-Paragraph 7
-Article 12

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 14
-Paragraph Column E
-Article 12

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 13
-Paragraph Column C
-Article 12

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12C
-Paragraph Column C
-Article 12

+ Details

Investment Securities - Additional Information (Detail) - USD ($)
$ in Thousands

Jun. 30, 2013

Dec. 31, 2012

^[1]

Schedule of Investments [Line Items]

Available-for-sale investment securities

$ 181,204

$ 50,068

Maturity dates more than 1 and less than 2 years

Schedule of Investments [Line Items]

Available-for-sale investment securities

$ 25,800

[1]	The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Investment, fair value disclosure	$ 204,633	$ 107,598

Fair Value Measurements of Cash Equivalents and Available-For-Sale Investment Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	$ 204,633	$ 107,598
Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	6,692	51,216
U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure		2,030
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	95,477	54,352
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	40,583
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure	61,881
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	6,692	53,246
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 and cash equivalents, fair value disclosure	6,692	51,216
Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value disclosure		2,030
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value disclosure	197,941	54,352
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	95,477	$ 54,352
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	40,583
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	$ 61,881

Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended		12 Months Ended
	May 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Shareholder Rights [Line Items]
Proceeds from sale of Common stock	$ 107,900	$ 110,079	$ 98
Share of common stock issued	9,200,000			5,347,137
Underwriter [Member]
Shareholder Rights [Line Items]
Share of common stock issued	1,200,000

Collaborative Research and Licensing Agreements - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) Contract	Jun. 30, 2012 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, revenue recognized	$ 451,000	$ 599,000	$ 868,000	$ 1,049,000
Allergan, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of collaboration agreements \| Contract			3
Collaboration agreement, payments received			$ 19,500,000
Collaboration agreement, original research term			3 years
Collaboration agreement, beginning date			2003-03
Collaboration agreement, revenue recognized	257,000	285,000	$ 544,000	548,000
Allergan, Inc. \| Glaucoma Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, payments received			9,900,000
Collaboration agreement, estimated development and regulatory milestones	15,500,000		15,500,000
Allergan, Inc. \| Chronic Pain Collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, payments received			10,500,000
Collaboration agreement, estimated development and regulatory milestones	$ 10,000,000		10,000,000
Meiji Seika Pharma Co., Ltd.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement, revenue recognized		$ 109,000		$ 222,000
Collaboration agreement, license fees			$ 3,000,000

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	May 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Supply Commitment [Line Items]
Share of common stock issued	9,200,000		5,347,137
Common stock rescission
Supply Commitment [Line Items]
Amount of common stock issued subject to rescission			$ 17.7
Maximum
Supply Commitment [Line Items]
Development services		$ 12.3