Receptos (RCPT) 10-K 6 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 28, 2014	Jun. 28, 2013
Document and Entity Information	'	'	'
Entity Registrant Name	'Receptos, Inc.	'	'
Entity Central Index Key	'0001463729	'	'
Document Type	'10-K	'	'
Document Period End Date	31-Dec-13	'	'
Amendment Flag	'false	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Non-accelerated Filer	'	'
Entity Public Float	'	'	$142,353,486
Entity Common Stock, Shares Outstanding	'	22,167,602	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$23,805	$5,427
Short-term investments	45,685	'
Prepaid expenses and other current assets	914	709
Total current assets	70,404	6,136
Property and equipment, net	269	549
Other assets	555	218
Total assets	71,228	6,903
Current liabilities:	'	'
Accounts payable	5,096	1,019
Accrued expenses	7,612	1,870
Accrued compensation and benefits	1,998	1,028
Current portion of term loan	735	'
Current portion of deferred revenue	700	2,225
Total current liabilities	16,141	6,142
Term loan	4,180	'
Deferred revenue, less current portion	'	700
Deferred rent	112	228
Total liabilities	20,433	7,070
Stockholders' equity (deficit):	'	'
Preferred stock, $0.001 par value; 10,000 and 0 shares authorized at December 31, 2013 and 2012, respectively; no shares issued and outstanding	'	'
Common stock, $0.001 par value; 200,000 and 113,533 shares authorized at December 31, 2013 and 2012, respectively; 18,350 and 2,417 shares issued and outstanding at December 31, 2013 and 2012, respectively	18	2
Additional paid-in capital	146,680	7,604
Accumulated comprehensive income	6	'
Accumulated deficit	-95,909	-47,589
Total stockholders' equity (deficit)	50,795	-39,983
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	71,228	6,903
Series A	'	'
Convertible preferred stock:	'	'
Convertible Preferred Stock	'	27,260
Stockholders' equity (deficit):	'	'
Total stockholders' equity (deficit)	'	27,260
Series B	'	'
Convertible preferred stock:	'	'
Convertible Preferred Stock	'	12,556
Stockholders' equity (deficit):	'	'
Total stockholders' equity (deficit)	'	$12,556

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	200,000,000	113,533,000
Common stock, shares issued	18,350,000	2,417,000
Common stock, shares outstanding	18,350,000	2,417,000
Series A convertible preferred stock	'	'
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	0	39,376,000
Preferred stock, shares issued	0	39,376,000
Preferred stock, shares outstanding	0	39,376,000
Series B convertible preferred stock	'	'
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	0	48,544,000
Preferred stock, shares issued	0	12,358,000
Preferred stock, shares outstanding	0	12,358,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Statements of Operations and Comprehensive Loss	'	'	'
Collaborative revenue	$4,641	$8,647	$9,232
Operating expenses:	'	'	'
Research and development	43,585	22,927	12,803
General and administrative	8,949	3,430	2,756
Total operating expenses	52,534	26,357	15,559
Loss from operations	-47,893	-17,710	-6,327
Other income (expense):	'	'	'
Interest income	27	18	7
Interest expense	-443	'	'
Other income (expense), net	-11	-18	210
Net loss	-48,320	-17,710	-6,110
Preferred stock deemed dividend	-2,056	'	'
Net loss attributable to common stockholders	-50,376	-17,710	-6,110
Net loss per share:	'	'	'
Net loss per common share, basic and diluted (in dollars per share)	($4.23)	($13.73)	($7.72)
Weighted-average shares used to compute basic and diluted net loss per common share (in shares)	11,916	1,289	791
Comprehensive loss:	'	'	'
Net loss	-48,320	-17,710	-6,110
Unrealized gain on marketable securities	6	'	'
Comprehensive loss	($48,314)	($17,710)	($6,110)

Consolidated_Statements_of_Con

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity/ (Deficit) (USD $)	Total	Series A convertible preferred stock	Series B convertible preferred stock	Common stock	Additional paid-in capital	Accumulated Comprehensive Income	Accumulated deficit
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2010	($16,699)	$18,744	'	$2	$7,068	'	($23,769)
Balance (in shares) at Dec. 31, 2010	'	26,964,000	'	1,649,000	'	'	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'
Net loss	-6,110	'	'	'	'	'	-6,110
Stock-based compensation expense	62	'	'	'	62	'	'
Issuance of series A convertible preferred stock and common stock warrants	148	8,516	'	'	148	'	'
Issuance of series A convertible preferred stock and common stock warrants (in shares)	'	12,412,000	'	'	'	'	'
Issuance of common stock, net of repurchase liability and including vesting of stock option early exercises	11	'	'	'	11	'	'
Issuance of common stock, net of repurchase liability and including vesting of stock option early exercises (in shares)	'	'	'	72,000	'	'	'
Repurchase of unvested common stock	-1	'	'	'	-1	'	'
Repurchase of unvested common stock (in shares)	'	'	'	-7,000	'	'	'
Issuance of common stock upon exercise of warrants	2	'	'	'	2	'	'
Issuance of common stock upon exercise of warrants (in shares)	'	'	'	25,000	'	'	'
Vesting of restricted common stock subject to repurchase	20	'	'	'	20	'	'
Balance at Dec. 31, 2011	-22,567	27,260	'	2	7,310	'	-29,879
Balance (in shares) at Dec. 31, 2011	'	39,376,000	'	1,739,000	'	'	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'
Net loss	-17,710	'	'	'	'	'	-17,710
Stock-based compensation expense	220	'	'	'	220	'	'
Issuance of Series B convertible preferred stock	'	'	12,556	'	'	'	'
Issuance of Series B convertible preferred stock (in shares)	'	'	12,358,000	'	'	'	'
Issuance of common stock, net of repurchase liability and including vesting of stock option early exercises	43	'	'	'	43	'	'
Issuance of common stock, net of repurchase liability and including vesting of stock option early exercises (in shares)	'	'	'	550,000	'	'	'
Issuance of common stock upon exercise of warrants	10	'	'	'	10	'	'
Issuance of common stock upon exercise of warrants (in shares)	'	'	'	128,000	'	'	'
Vesting of restricted common stock subject to repurchase	21	'	'	'	21	'	'
Balance at Dec. 31, 2012	-39,983	27,260	12,556	2	7,604	'	-47,589
Balance (in shares) at Dec. 31, 2012	'	39,376,000	12,358,000	2,417,000	'	'	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'
Net loss	-48,320	'	'	'	'	'	-48,320
Unrealized gain on market securities	6	'	'	'	'	6	'
Stock-based compensation expense	2,969	'	'	'	2,969	'	'
Issuance of Series B convertible preferred stock	'	'	21,192	'	'	'	'
Issuance of Series B convertible preferred stock (in shares)	'	'	20,596,000	'	'	'	'
Preferred stock deemed dividend	-2,056	'	2,056	'	-2,056	'	'
Conversion of convertible preferred stock into common	63,064	-27,260	-35,804	10	63,054	'	'
Conversion of convertible preferred stock into common (in shares)	'	-39,376,000	-32,954,000	9,644,000	'	'	'
Initial public offering of common stock	75,009	'	'	6	75,003	'	'
Initial public offering of common stock (in shares)	'	'	'	5,933,000	'	'	'
Vesting of restricted common stock subject to repurchase	79	'	'	'	79	'	'
Issuance of common stock upon exercise of options and warrants	27	'	'	'	27	'	'
Issuance of common stock upon exercise of options and warrants (in shares)	'	'	'	356,000	'	'	'
Balance at Dec. 31, 2013	$50,795	'	'	$18	$146,680	$6	($95,909)
Balance (in shares) at Dec. 31, 2013	'	'	'	18,350,000	'	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities	'	'	'
Net loss	($48,320)	($17,710)	($6,110)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:	'	'	'
Stock-based compensation	2,969	220	62
Depreciation and amortization	350	656	827
Deferred rent	-116	27	-142
Other	213	'	'
Change in operating assets and liabilities:	'	'	'
Prepaid expenses and other assets	-388	-278	-101
Accounts payable	4,077	557	26
Accrued expenses	5,643	122	1,089
Accrued compensation and benefits	970	216	382
Deferred revenue	-2,225	-2,228	5,153
Net cash (used in) provided by operating activities	-36,827	-18,418	1,186
Investing activities	'	'	'
Purchases of marketable securities	-45,743	'	'
Purchases of property and equipment	-70	-214	-614
Net cash used in investing activities	-45,813	-214	-614
Financing activities	'	'	'
Net proceeds from issuance of convertible preferred stock and common stock warrants	21,192	12,556	8,664
Net proceeds from initial public offering	75,009	'	'
Net proceeds from borrowings under term loan	4,790	'	'
Proceeds from exercise of common stock options and warrants	27	41	13
Proceeds from early exercises of stock options	'	126	11
Repurchase of unvested restricted stock	'	'	-1
Net cash provided by financing activities	101,018	12,723	8,687
Net increase (decrease) in cash and cash equivalents	18,378	-5,909	9,259
Cash and cash equivalents at beginning of period	5,427	11,336	2,077
Cash and cash equivalents at end of period	23,805	5,427	11,336
Supplemental disclosure of cash flow information:	'	'	'
Conversion of Series A and B Preferred Stock to common stock	63,064	'	'
Accrued expenses relating to deferred initial public offering costs	254	77	'
Release of repurchase liability for stock options and restricted stock shares	79	32	28
Cash paid for interest	259	'	'
Non-cash financing activity:	'	'	'
Preferred stock deemed dividend	$2,056	'	'

Description_of_Business

Description of Business	12 Months Ended
	Dec. 31, 2013
Description of Business	'
Description of Business	'
	1. Description of Business
	Receptos, Inc. is a biopharmaceutical company focused on discovering, developing and commercializing innovative therapeutics in immune disease for specialty markets including for Relapsing Multiple Sclerosis (RMS), Inflammatory Bowel Disease (IBD) and Eosinophilic Esophagitis (EoE). The Company was incorporated in the state of Delaware on September 26, 2008 under the name Receptor Pharmaceuticals, Inc., and commenced significant operations in 2009. As used in this report, unless the context suggests otherwise, "the Company" and "Receptos" mean Receptos, Inc.
	The consolidated financial statements include the accounts of Receptos, Inc. and its wholly-owned subsidiary, Apoptos, Inc. (Apoptos), which is currently inactive. All intercompany balances and transactions among the consolidated entities have been eliminated in consolidation.
	Liquidity
	The Company has incurred losses since inception and negative cash flows from operating activities and, as of December 31, 2013, the Company had an accumulated deficit of $95.9 million. The Company anticipates that it will continue to incur net losses into the foreseeable future as it: (i) continues the development and commercialization of its lead drug candidate RPC1063; (ii) works to develop additional drug candidates through research and development programs; and (iii) expands its corporate infrastructure. The Company had cash, cash equivalents and short-term investments of $69.5 million as of December 31, 2013, and in January 2014 conducted an underwritten public offering that generated net proceeds of $109.9 million. The Company plans to continue to fund its losses from operations and capital funding needs through cash and investments on hand, as well as future debt and equity financing and potential collaboration arrangements. If the Company is not able to secure adequate additional funding, it may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. Any of these actions could materially harm the Company's business, results of operations and future prospects.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Use of Estimates
	The Company's consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (US GAAP). The preparation of the Company's consolidated financial statements requires management to make informed estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company's consolidated financial statements and accompanying notes. The most significant estimates in the Company's consolidated financial statements relate to clinical trial accruals and revenue recognition. Although these estimates are based on the Company's knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
	Segment Reporting
	Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment operating primarily in the US.
	Cash and Cash Equivalents
	The Company classifies time deposits and other investments that are highly liquid and have maturities of 90 days or less at the date of purchase as cash equivalents. The carrying amounts approximate fair value due to the short maturities of these instruments. Cash and cash equivalents include cash in readily available checking and money market accounts, as well as corporate debt securities.
	Short-Term Investments
	The Company carries short-term investments classified as available-for-sale at fair value as determined by prices for identical or similar securities at the balance sheet date. Short-term investments consist of both Level 1 and Level 2 financial instruments in the fair value hierarchy. The Company records unrealized gains and losses as a component of other comprehensive loss within the statements of operations and comprehensive loss and as a separate component of stockholders' equity (deficit). Realized gains or losses of available-for-sale securities is determined using the specific identification method and we include net realized gains and losses in interest income.
	At each balance sheet date, the Company assesses available-for-sale securities in an unrealized loss position to determine whether the unrealized loss is other-than-temporary. The Company considers factors including: the significance of the decline in value compared to the cost basis, underlying factors contributing to a decline in the prices of securities in a single asset class, the length of time the market value of the security has been less than its cost basis, the security's relative performance versus its peers, sector or asset class, expected market volatility and the market and economy in general. An impairment loss is recognized at the time the Company determines that a decline in the fair value below its cost basis is other-than-temporary.
	Fair Value of Financial Instruments
	The valuation of assets and liabilities are subject to fair value measurements using a three tiered approach and fair value measurement is classified and disclosed by the Company in one of the following three categories:
	Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;
	Level 2: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability;
	Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e. supported by little or no market activity).
	The carrying amounts of all cash equivalents, short-term investments, accounts payable and accrued liabilities are reasonable estimates of their fair value because of the short-term nature of these items.
	Concentrations of Credit Risk
	Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.
	Property and Equipment
	Property and equipment is carried at cost and depreciation is computed using the straight-line method over the estimated useful lives of the assets (generally three to seven years). The Company amortizes leasehold improvements over the lease term or the useful life of the improvement, whichever is shorter (including any renewal periods that are deemed to be reasonably assured). The Company expenses repair and maintenance costs that do not improve service potential or extend economic life as incurred.
	Impairment of Long-Lived Assets
	The Company reviews property and equipment for impairment on an annual basis and whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. An impairment loss would be recognized when estimated future undiscounted cash flows relating to the asset are less than its carrying amount. An impairment loss is measured as the amount by which the carrying amount of an asset exceeds its fair value. While the Company's current and historical operating losses and negative cash flows are possible indicators of impairment, management believes that the future cash flows to be generated by these assets support the carrying value of its long-lived assets and, accordingly, has not recognized any significant impairment losses during the years ended December 31, 2013, 2012 and 2011.
	Income Taxes
	The accounting guidance for uncertainty in income taxes prescribes a recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position.
	The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made.
	Revenue Recognition
	The Company enters into arrangements with pharmaceutical and biotechnology partners that may involve multiple deliverables. The Company's arrangements may contain upfront payments, license fees for research and development arrangements, research and development funding and milestone payments under collaborative agreements. Each deliverable in the arrangement is evaluated to determine whether it meets the criteria to be accounted for as a separate unit of accounting or whether it should be combined with other deliverables. Revenue is recognized separately for each unit of accounting when all four of the following criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured.
	Upfront Fees.    When management determines the Company has a single unit of accounting under its collaborative arrangements, upfront fees received for collaborative agreements are recognized ratably over the expected performance period under each respective arrangement. As a result, management makes its best estimate of the period over which the Company expects to fulfill its performance obligations under that agreement. Any amounts received under the agreements in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.
	Milestones.    The Company evaluates all milestones at the beginning of the agreement to determine if they meet the definition of a substantive milestone. Revenue is recognized from milestone payments when earned, provided that (i) the milestone event is substantive in that it can only be achieved based in whole or in part on either the Company's performance or on the occurrence of a specific outcome resulting from the Company's performance and its achievability was not reasonably assured at the inception of the agreement, (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone and (iii) it would result in the receipt of additional payments. A milestone payment is considered substantive if all of the following conditions are met: (i) the milestone payment is non-refundable; (ii) achievement of the milestone was not reasonably assured at the inception of the arrangement; (iii) substantive effort is involved to achieve the milestone; and (iv) the amount of the milestone payments appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone.
	Deferred Revenue.    Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized within the next 12 months are classified as non-current deferred revenue.
	Research and Development
	Research and development (R&D) expenses include the costs associated with the Company's R&D activities, including salaries, benefits and occupancy costs. Also included in R&D expenses are third-party costs incurred in conjunction with contract manufacturing for the Company's R&D programs and clinical trials, including the cost of clinical trial drug supply shipped to its clinical study vendors, regulatory expenses and costs incurred by contract research organizations (CROs). R&D costs are expensed as incurred, except when accounting for nonrefundable advance payments for goods or services to be used in future R&D activities. These payments are capitalized at the time of payment and expensed ratably over the period the R&D activity is performed.
	Clinical Study Costs and Clinical Trial Accruals
	The Company accounts for a significant portion of its clinical study costs according to the terms of its contracts with CROs. The financial terms of its CRO contracts may result in payment flows that do not match the periods over which materials or services are provided to us under such contracts. The Company's objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. As part of the process of preparing its financial statements, the Company relies on cost information provided by its CROs (concerning monthly expenses as well as reimbursement for pass through costs). The Company is also required to estimate certain of its expenses resulting from its obligations under its CRO contracts. Accordingly, the Company's clinical trial accrual is dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.
	Stock-Based Compensation
	The Company accounts for stock-based compensation expense related to stock options granted to employees and members of its board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes options-pricing model, net of estimated forfeitures. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized using the straight-line method. In accordance with the authoritative accounting literature, options subject to both performance and time-based vesting conditions are expensed using an accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), compensation expense is recognized over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition during the earlier vesting periods. The Company accounts for stock options granted to non-employees using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms.
	For performance-based awards to employees (i) the fair value of the award is determined on the grant date, (ii) the Company assesses the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. For performance-based awards to non-employees, no expense is recognized until such time as the milestone event is achieved. Upon achievement, the portion of the milestone subject to immediate vesting is expensed based upon the then fair value of the award. For the portion of the award further subject to time-based vesting restrictions, expense is recorded quarterly, at the then fair value, as the shares vest until such time as performance is complete.
	Comprehensive Loss
	Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources.
	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 calculated by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of convertible preferred stock, stock options and warrants. The calculation of the weighted-average number of shares outstanding excludes shares which have been issued upon the early exercise of stock options and are subject to future vesting and unvested restricted stock totaling 0.5 million and 0.9 million shares as of December 31, 2013 and 2012, respectively.
	Basic and diluted net loss per share are equivalent because the Company has incurred a net loss in all periods presented causing any potentially dilutive securities to be anti-dilutive. Potentially dilutive securities totaled 3.8 million, 6.9 million and 5.3 million shares of common stock as of December 31, 2013, 2012 and 2011, respectively.
	Reclassification of Prior Period Balances
	Certain reclassifications have been made to prior period amounts to conform to current-year presentation.
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board issued an accounting standard update to require reclassification adjustments from other comprehensive income to be presented either in the financial statements or in the notes to the financial statements. This accounting standard became effective for the Company beginning in the first quarter of fiscal 2013, and its adoption did not have any impact on the Company's consolidated financial statements.

ShortTerm_Investments

Short-Term Investments	12 Months Ended
	Dec. 31, 2013
Short-Term Investments.	'
Short-Term Investments	'
	3. Short-Term Investments
	The Company invests in available-for-sale securities consisting of money market funds, commercial paper and debt instruments of financial institutions and corporations. Available-for-sale securities are classified as part of either cash equivalents or short-term investments in the balance sheets. Available-for-sale securities with maturities of three months or less from date of purchase have been classified as cash equivalents, and amounted to $19.1 million as of December 31, 2013. The carrying value of available for sale securities classified as short-term investments consisted of the following as (in thousands):
		As of December 31, 2013
		Amortized		Unrealized		Unrealized			Fair Market
		Cost		Gains		Losses			Value
	Commercial paper	$	18,927	$	17	$	—		$	18,944
	Corporate debt securities		26,752		—		(11	)		26,741
	Total	$	45,679	$	17	$	(11	)	$	45,685
	The Company determined that there were no other-than-temporary declines in the value of any available-for-sale investment securities as of December 31, 2013. The Company did not hold any available-for-sale investment securities as of December 31, 2012. All of the Company's available-for-sale investment securities mature within one year.
	Available-for-sale investment securities are classified within the fair value hierarchy as defined by authoritative guidance. The majority of the Company's securities have been classified as Level 2. The Company obtains the fair value of its Level 2 investments from the custodian bank or from a professional pricing service. The fair value of Level 2 investments is validated by comparing the fair values reported by the custodian bank to fair values obtained from a second source professional pricing service. The Company has not transferred any investment securities between the classifications. The fair value of the Company's investment holdings is summarized in the following table (in thousands):
		As of December 31, 2013
				Fair Value Determined Under
		Total Fair
		Value		(Level 1)		(Level 2)			(Level 3)
	Money market funds	$	8,147	$	8,147	$	—		$	—
	Commercial paper		18,944		—		18,944			—
	Corporate debt securities		37,649		—		37,649			—
	Total	$	64,740	$	8,147	$	56,593			—

Balance_Sheet_Details

Balance Sheet Details	12 Months Ended
	Dec. 31, 2013
Balance Sheet Details	'
Balance Sheet Details	'
	4. Balance Sheet Details
	Prepaid Expenses and Other Current Assets
	The following table summarizes major classes of prepaid expenses and other current assets (in thousands):
		December 31,
		2013			2012
	Prepaid insurance	$	321		$	62
	Interest receivable		277			—
	Prepaid contract research costs		—			435
	Prepaid other		316			212
	Total	$	914		$	709
	Property and Equipment
	The following table summarizes major classes of property and equipment (in thousands):
				December 31,
		Useful
		life		2013			2012
	Laboratory equipment	3 years		$	2,860		$	2,940
	Computer equipment and software	3 years			150			226
	Leasehold improvements	7 years			854			854
					3,864			4,020
	Less accumulated depreciation and amortization				3,595			3,471
	Property and equipment, net			$	269		$	549
	Accrued Expenses
	The following table summarizes major classes of accrued liabilities (in thousands):
		December 31,
		2013			2012
	Accrued clinical trial services	$	3,197		$	1,289
	Accrued royalty payable		550			176
	Repurchase liability for unvested restricted stock awards		108			188
	Other accrued liabilities		3,757			217
	Total	$	7,612		$	1,870

Collaborative_Arrangements

Collaborative Arrangements	12 Months Ended
	Dec. 31, 2013
Collaborative Arrangements	'
Collaborative Arrangements	'
	5. Collaborative Arrangements
	The Company has entered into various license agreements and collaborative research and development arrangements with pharmaceutical and biotechnology companies. Under these arrangements, the Company is entitled to receive license fees, upfront payments, milestone payments when and if certain research or technology transfer milestones are achieved, development milestones in one instance based solely upon the Company's partner's performance and/or reimbursement for research and development activities. The Company's costs of performing these services are included in research and development expense.
	The Company recognized revenue under these arrangements as follows (in thousands):
		Year ended December 31,
	Partner	2013		2012		2011
	Ono Pharmaceutical Co., Ltd.	$	4,641	$	6,088	$	212
	Eli Lilly and Company		—		2,480		2,520
	Ortho-McNeil-Janssen Pharmaceuticals		—		79		6,500
	Collaborative revenue	$	4,641	$	8,647	$	9,232
	Collaboration with Ono Pharmaceutical Co., Ltd.    In December 2011, the Company entered into a co-exclusive Collaboration Agreement, or the Ono Agreement, with Ono to utilize the Company's proprietary GPCR structure determination technologies for the identification of a high resolution novel protein crystal structure of an Ono proprietary GPCR drug discovery target. In December 2011, Ono paid the Company an upfront fee of $2.5 million as consideration for technology access. It was determined that there was one unit of accounting under the Ono Agreement with respect to this upfront fee and, as such, this fee is being recognized as collaborative revenue on a straight-line basis over the expected period of performance of the amended contract. The Ono Agreement also called for Ono to pay the Company for research and development support, and these quarterly support payments were recognized as collaborative revenue as services were provided. Such revenues totaled $2.7 million, $2.6 million and $0.1 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	The Ono Agreement also provides for payments to the Company upon achievement of certain milestone events. The Company concluded that certain of these milestone payments did not meet the definition of a substantive milestone, inasmuch as achievability was reasonably assured at the inception of the Ono Agreement. Such revenue was deferred and is being amortized over the contract term. Additionally, operating results for the years ended December 31, 2013 and 2012 include collaborative revenues of $0.3 million and $2.0 million, respectively, associated with achievement of research milestones that the Company's management determined did satisfy the criteria for treatment as substantive milestones. There was no similar substantive milestone revenue for the year ended December 31, 2011.
	In December 2013, the Ono Agreement was amended to allow for the early termination of the research term of the underlying collaboration and the Company agreed to perform technology transfer with respect to, and to grant Ono a non-exclusive sublicense to, the Company's GPCR technology platform for high resolution crystal structure determination. Pursuant to the amendment, the Company is entitled to receive upfront license and collaborative research termination fees totaling $3.7 million, is eligible to receive technology transfer milestone payments of up to $2.0 million, and is also providing training services in support of Ono's efforts to achieve certain technology transfer milestones. Such revenue will be recognized prospectively over the expected period of performance of the amended contract.
	Under the Collaboration Agreement, as amended, the Company also remains eligible as of December 31, 2013, for research milestone payments of up to another $2.0 million based on successful completion of certain research activities and for development milestone payments of up to $13.5 million for the achievement of development milestones based solely upon Ono's performance.
	Eli Lilly and Company.    In December 2010, the Company entered into a two year co-exclusive Collaborative Agreement with Eli Lilly and Company, or Lilly, to utilize its proprietary GPCR structure determination technologies, including application of such technologies to the development of potential modulators directed to an undisclosed GPCR target. In January 2011, as consideration for technology access over the term, Lilly paid the Company an upfront, non-refundable fee of $5.0 million. It was determined that there was one unit of accounting under the Lilly contract. As a result, the $5.0 million non-refundable fee was recognized on a straight-line basis over two years, which was the contract term. The agreement expired on December 31, 2012, and the Company does not expect to receive any future milestone payments from Lilly. Each of the Company and Lilly retain the right to use the research and development know-how for future research activities.
	License and Technology Transfer Agreement with Janssen Pharmaceuticals, Inc.    In December 2010, the Company entered into a License and Technology Transfer Agreement with Ortho-McNeil-Janssen Pharmaceuticals, or OMJP, in which OMJP sublicensed the Company's proprietary platform for high resolution crystal structure determination (the Company holds an exclusive license for this technology which was originally licensed from The Scripps Research Institute). In February 2011, as consideration for the sublicense and a technology transfer program, OMJP paid an upfront, non-refundable fee of $4.0 million. This fee was recognized on a straight-line basis during fiscal 2011, which was the period during which the Company performed services for OMJP. The technology transfer program was completed as of December 7, 2011, and OMJP paid the Company a milestone of $2.5 million. The agreement concluded at that time, and the Company does not expect to receive any future payments from OMJP.

Term_Loan_and_Security_Agreeme

Term Loan and Security Agreement	12 Months Ended
	Dec. 31, 2013
Term Loan and Security Agreement	'
Term Loan and Security Agreement	'
	6. Term Loan and Security Agreement
	On April 19, 2013, the Company entered into a credit and security agreement with MidCap Funding III, LLC allowing for borrowings up to $30.0 million. The credit and security agreement provides for the loan to be issuable in three equal tranches of $10.0 million, with availability of funds contingent upon attainment of stipulated milestones. The Company borrowed $5.0 million under this facility during 2013. The interest rate under the credit and security agreement is 8.25%, and there is an interest only period until August 1, 2014, followed by a 34-month principal and interest period. Any unpaid amounts mature and become payable on May 1, 2017. Pursuant to the credit and security agreement, the Company provided a first priority security interest in all existing and after-acquired assets (excluding intellectual property owned by the Company, which is subject to a negative pledge arrangement).
	As of December 31, 2013, the Company's available borrowing capacity under this facility was $15.0 million. These funds are available to the Company through March 31, 2014. Additionally, upon achievement of certain criteria, the Company will be able to borrow up to an additional $10.0 million under the facility through December 31, 2014.
	The loan was recorded at its initial carrying value of $5.0 million, less the debt discount of $0.2 million. The debt discount included an initial fee and certain reimbursed costs of the transaction paid to the lender. At the time of final payment of the loan, the Company must also pay an exit fee based on a percentage of the drawn amount to the lender (as of December 31, 2013, the exit fee obligation is $350,000). In addition, if the Company's repayment obligation is accelerated following an event of default, or if the Company elects to prepay any portion of the loan, the Company must also pay a prepayment fee of 3% of the principal being repaid (dropping to 2% after August 18, 2014 then to 1% after December 18, 2015). The debt discount and the exit fee are being accreted to interest expense over the loan term.
	Future principal payments due under the loan agreement are as follows (in thousands):
	2014	$	735
	2015		1,765
	2016		1,765
	2017		735
	Total future principal payments due under loan agreement	$	5,000

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies	'
Commitments and Contingencies	'
	7. Commitments and Contingencies
	License Agreements
	The Company has license agreements with The Scripps Research Institute, or TSRI, that require it to make annual license maintenance payments and future payments upon the success of licensed products that include milestones and/or royalties. Royalties are expensed as incurred and are included in research and development in the consolidated statements of operations and comprehensive loss.
	S1P1R Modulators License Agreement.    In April 2009, the Company entered into a License Agreement with TSRI, whereby the Company received an exclusive worldwide license under the Licensed Patent Rights, as defined, for S1P1R modulators and a non-exclusive worldwide license to the Licensed Materials, as defined. In consideration, the Company (i) agreed to pay a nominal annual maintenance fee, (ii) is responsible for paying royalties on annual net Sales of Licensed Product ranging between 1.5% and 2.0%, for Licensed Product until such time as the expiration of the last valid claim, (iii) is responsible for paying royalties ranging between 0.75% and 1.0%, on annual net Sales of Non-Patent Product until such time as one or more generic versions of such Non-Patent Product are commercially sold and the Company demonstrates to TSRI that sales of such generic products account for a specific percentage of aggregate unit sales in a calendar quarter, (iv) is responsible for paying product development milestone payments not to exceed $4.4 million and (v) is responsible for paying a percentage of any sublicense revenue payments received by the Company.
	In each of the years ended December 31, 2013, 2012 and 2011, consideration paid to TSRI under this agreement was $25,000, $10,000 and $10,000, respectively. Included in accrued liabilities in the consolidated balance sheet as of December 31, 2013 are accrued royalties associated with this agreement of $0.3 million.
	Technology Platform License Agreement.    In June 2009, the Company entered into a Technology Platform License Agreement with TSRI whereby the Company received an exclusive worldwide license under the Licensed Patent Rights, as defined, and a non-exclusive worldwide license under the Know-How, as defined. In consideration, the Company (i) agreed to pay a nominal annual maintenance fee beginning after June 18, 2011, which is credited against running royalties during the term of the Agreement, (ii) agreed to pay running royalties at a de minimus rate of annual Net Sales of Company Products until June 18, 2019, (iii) agreed to pay product development milestone payments not to exceed approximately $1.0 million and (iv) is required to make non-creditable, non-refundable Aggregate Technology Income (ATI), as defined, payments of 7.5% of the first $100 million of cumulative ATI, except that no ATI payments is due on the first $2.5 million in cumulative ATI and a reduced percentage of that portion of cumulative ATI that is in excess of $100 million. All product development milestone and ATI payments are payable up to June 18, 2027.
	Royalty consideration paid to TSRI under this agreement for the years ended December 31, 2013, 2012 and 2011, was $0.2 million, $0.5 million and $0.4 million, respectively. Included in accrued liabilities in the consolidated balance sheet as of December 31, 2013 are accrued royalties associated with this agreement of $0.2 million.
	Operating Lease
	The Company's lease to rent laboratory and office space in San Diego, California commenced in March 2008 and as amended, expires in October 2014. The Company also has two options to extend the lease for successive three-year periods. Under the terms of the lease the Company maintains a letter of credit totaling $0.1 million. The Company recognizes minimum rent payments and escalation clauses on a straight-line basis over the lease term of March 2008 through October 2014. The Company accounts for the difference between the minimum lease payments and the straight-line amount as deferred rent. Rent expense for the years ended December 31, 2013, 2012 and 2011 was $0.9 million, $0.8 million and $0.5 million, respectively. As of December 31, 2013, the Company's remaining future minimum commitments under this facility lease total $0.5 million (which will be paid during fiscal 2014). The Company also pays property taxes, maintenance and insurance, in addition to rent.
	Other Commitments
	In connection with certain long-term contractual obligations, the Company is obligated to make payments of up to $7.7 million over the next twelve months.
	Litigation
	From time to time, the Company may be involved in various lawsuits, legal proceedings, or claims that arise in the ordinary course of business. Management does not believe any legal proceedings or claims pending at December 31, 2013, will have, individually or in the aggregate, a material adverse effect on its business, liquidity, financial position or results of operations. Litigation, however, is subject to inherent uncertainties, and an adverse result in these or other matters may arise from time to time that may harm the Company's business.

Convertible_Preferred_Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2013
Convertible Preferred Stock	'
Convertible Preferred Stock	'
	8. Convertible Preferred Stock
	Authorized Shares
	In May 2013, the Company completed an initial public offering ("IPO") of its common stock. Prior to the IPO, the Company was authorized to issue 39,376,000 shares of Series A convertible preferred stock and 48,544,000 shares of Series B convertible preferred stock. The Company's convertible preferred stock was classified as temporary equity in the accompanying consolidated balance sheet at December 31, 2012 instead of in stockholders' equity (deficit) in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities. Upon certain change in control events that were outside of the Company's control, including liquidation, sale or transfer of control of the Company, holders of the convertible preferred stock could have caused its redemption.
	Issuance of Series A and Series B Convertible Preferred Stock
	In June and December 2011, the Company issued 12,412,000 shares of Series A convertible preferred stock at $0.70 per share for net cash proceeds of $8.7 million. In February and March 2012, the Company issued 12,358,000 shares of Series B convertible preferred stock at $1.03 per share for net proceeds of $12.6 million. In February 2013, the Company closed a second tranche financing for 12,358,000 shares of Series B convertible preferred stock at $1.03 per share for net proceeds of $12.7 million. In March 2013, the Company closed a third tranche financing issuing 8,238,000 shares of Series B convertible preferred stock at $1.03 per share for net proceeds of $8.5 million.
	The Series B stock issued in March 2013 was sold at a price per share below the reassessed deemed fair value of the Company's common stock at that time. Accordingly, the Company recorded a deemed dividend of $2.1 million associated with the issuance of such shares, which is equal to the number of shares of stock sold on that date multiplied by the difference between the estimated value of the underlying common stock and the Series B conversion price per share on that date.
	Conversion of Series A and Series B Convertible Preferred Stock
	On May 14, 2013, the 72,330,000 outstanding shares of convertible preferred stock automatically converted into an aggregate of 9,644,000 shares of common stock immediately prior to the closing of the IPO.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity	'
Stockholders' Equity	'
	9. Stockholders' Equity
	Preferred Stock
	In May 2013, the Company filed an amended and restated certificate of incorporation to authorize 10,000,000 shares of undesignated preferred stock.
	Common Stock
	Reverse Stock Split.    On April 25, 2013, the Company implemented a 1-for-7.5 reverse stock split of its outstanding common stock. The accompanying consolidated financial statements give retroactive effect to the reverse split for all periods presented.
	Restricted Common Stock.    Prior to 2013, the Company issued restricted common stock to certain founders and officers of the Company with both performance-based and time-based vesting provisions. As of December 31, 2013, all remaining outstanding restricted shares are subject to time-based vesting that will lapse over the next two years. As of December 31, 2013, 163,000 shares associated with these restricted stock awards were subject to repurchase by the Company.
	The Company's 2008 Stock Plan allowed for the early exercise of option awards issued under the plan. As of December 31, 2013, options for the purchase of 982,000 shares of the Company's common stock (net of repurchased shares) have been exercised, of which 307,000 are unvested and subject to repurchase. Under the authoritative guidance, early exercise is not considered an exercise for accounting purposes and, therefore, any payment for unvested shares is recognized as a liability at the original exercise price. This repurchase obligation is included in accrued expenses in the consolidated balance sheets and is not material for any period presented. During the years ended December 31, 2013 and 2011, the Company repurchased 123 and 7,222 unvested shares, respectively, which were previously early exercised. During the year ended December 31, 2012, no shares were repurchased by the Company.
	Initial Public Offering.    In May 2013, the Company completed the IPO of 5,933,277 shares of common stock at an offering price of $14.00 per share. The Company received net proceeds of approximately $75.0 million, after deducting underwriting discounts, commissions and offering-related transaction costs of $8.1 million.

StockBased_Compensation_and_Eq

Stock-Based Compensation and Equity Plans	12 Months Ended
	Dec. 31, 2013
Stock-Based Compensation and Equity Plans	'
Stock-Based Compensation and Equity Plans	'
	10. Stock-Based Compensation and Equity Plans
	2013 Stock Incentive Plan
	Prior to the completion of the IPO, the Company issued stock options under its 2008 Stock Plan (the 2008 Plan). Effective upon the closing of the IPO, the Company's board of directors and stockholders approved the 2013 Stock Incentive Plan (the 2013 Plan). The 2013 Plan provides for the granting of incentive stock options, within the meaning of Section 422 of the Internal Revenue Code, to employees and the granting of nonstatutory stock options, restricted stock, stock appreciation rights, stock unit and cash-based awards to employees, non-employee directors, advisors and consultants. The Company has issued under the 2008 Plan and intends to continue to issue under the 2013 Plan both performance-based and time-based stock options and restricted stock awards. Performance-based awards generally vest 25% upon achievement of a milestone event, with monthly time-based vesting over the subsequent 36 months, while time-based awards generally vest over a four-year period commencing on the first anniversary of the date of grant. Milestone events are specific to corporate goals. Awards generally expire ten years from the date of grant.
	The number of shares of common stock available for future grant under the 2013 Plan upon its approval was 1,146,600 shares plus (i) the number of shares subject to outstanding awards under the 2008 Plan when the 2013 Plan was approved that are subsequently forfeited or terminated for any reason before being exercised or settled and (ii) the number of shares subject to vesting restrictions under the 2008 Plan when the 2013 Plan was approved that are subsequently forfeited. In addition, the number of shares of common stock that may be issued under the 2013 Plan is subject to an automatic annual increase equal to the lesser of (x) four percent of the outstanding shares on the last day of the immediately preceding fiscal year or (y) if the Company's board acts prior to the first day of the fiscal year, such other amount that the board determines for purposes of the annual increase for that fiscal year. Under this evergreen provision of the 2013 Plan, an additional 734,000 shares became available for future grant on January 1, 2014.
	Stock Options
	The following table summarizes stock option activity for the year ended December 31, 2013 (share amounts in thousands):
		# Shares			Weighted			Weighted
					Average			Average
					Exercise			Remaining
					Price			Contractual
					per Share			Term (years)
	Outstanding at December 31, 2012		59		$	0.3
	Granted		1,351			15.28
	Exercised		(13	)		0.27
	Outstanding at December 31, 2013		1,397		$	14.78			9.4
	Vested or expected to vest at December 31, 2013		741		$	0.82			6.5
	Exercisable at December 31, 2013		81		$	6.18			8.4
	A significant number of the Company's stock options have been early exercised and are not outstanding. As of December 31, 2013, vested or expected to vest included options for 307,000 shares which were early exercised and are still subject to future vesting (and which may be repurchased by the Company in the event the option holder ceases to provide services to the Company).
	The aggregate intrinsic value of options outstanding and exercisable as of December 31, 2013 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 $28.99. The aggregate intrinsic value of options outstanding and exercisable as of December 31, 2013 was $19.9 million. The aggregate intrinsic value of options exercised during the years ended December 31, 2013, 2012 and 2011 was approximately $0.3 million, $24,000 and $0, respectively, determined as of the date of exercise. The Company did not recognize any income tax benefits from stock option exercises as it continues to record a full valuation allowance on its deferred tax assets.
	Stock Compensation Expense
	The Company uses the Black-Scholes option pricing model to estimate the grant date fair value of its stock options. The weighted-average assumptions underlying the calculation of grant date fair value include the following:
		Year ended December 31,
		2013			2012			2011
	Risk free interest rate		1.4	%		1.1	%		2.2	%
	Expected term (years)		6.1			6			6.1
	Expected volatility		105.9	%		94.2	%		87.7	%
	Expected dividend yield		0	%		0	%		0	%
	The individual inputs are determined as follows:
	Risk-free interest rate.    The risk-free interest rate assumptions are based on observed interest rates appropriate for the expected term of the stock option grants.
	Expected term.    The expected term represents the period of time that options are expected to be outstanding. Because the Company does not have historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual term of the option and its ordinary vesting period.
	Expected volatility.    The expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry.
	Expected dividend yield.    The expected dividend yield assumption is based on the fact that the Company has never paid, nor has any intention to pay, cash dividends.
	Forfeitures.    The Company reduces stock-based compensation expense for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. To date forfeitures have been approximately 0.26% of total grants.
	The weighted average grant date fair value of options granted during the years ended December 31, 2013, 2012 and 2011 was approximately $15.28, $0.30 and $0.23, respectively.
	The following table summarizes share-based compensation expense for all awards granted (in thousands):
		Year ended December 31,
		2013			2012			2011
	Research and development	$	1,360		$	192		$	33
	General and administrative		1,609			28			29
	Total share-based compensation expense	$	2,969		$	220		$	62
	As of December 31, 2013, unrecognized compensation expense related to non-vested stock options totaled $16.1 million. Such compensation expense is expected to be recognized over a weighted-average period of 3.6 years.
	Employee Stock Purchase Plan
	Effective upon the closing of the IPO, the Company's board of directors and the stockholders approved the 2013 Employee Stock Purchase Plan (the ESPP). Upon implementation, the Company could originally issue up to 160,000 shares under the ESPP. The ESPP is subject to an automatic annual increase equal to the lesser of (i) one percent of the outstanding capital stock on each January 1 or (ii) an amount determined by the Company's board of directors. Under this evergreen provision of the ESPP, an additional 183,000 shares became available for future issuance on January 1, 2014.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Taxes	'
Income Taxes	'
	11. Income Taxes
	The following is a reconciliation of the expected statutory federal income tax provision to the actual income tax provision (in thousands):
		Year ended December 31,
		2013			2012			2011
	Expected income tax benefit at federal statutory tax rate	$	(16,429	)	$	(6,021	)	$	(2,077	)
	State income taxes, net of federal benefit		(2,694	)		(1,019	)		(320	)
	Permanent items		558			82			277
	Research credits		(2,393	)		(477	)		(1,096	)
	Removal of net operating losses and research and development credits		20,527			6,774			3,014
	Change in valuation allowance		431			661			202
	Income tax (benefit) expense	$	—		$	—		$	—
	The following table summarizes the significant components of deferred tax assets (in thousands):
		December 31,
		2013			2012
	Deferred tax assets:
	Depreciation and amortization	$	499		$	630
	Deferred revenue		279			564
	Stock options		543			—
	Accrued expenses and reserves		705			402
	Total deferred tax assets		2,026			1,596
	Less: Valuation allowance		2,026			1,596
	Net deferred tax assets	$	—		$	—
	In assessing the realizability of its deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. Based on the weight of all available evidence, including the Company's history of losses from inception, management has determined that it is not more likely than not that the net deferred tax assets will be realized. Accordingly, a full valuation allowance has been established to offset the net deferred tax asset for all periods presented.
	As of December 31, 2013, the Company had federal and California tax net operating loss carryforwards of $87.1 million and $87.2 million, respectively, which will begin to expire in 2027 and 2017, respectively. As of December 31, 2013, the Company also had federal and California research and development tax credit carryforwards of $4.0 million and $2.5 million, respectively. The federal research and development tax credit carryforwards will begin to expire in 2027. The California research and development tax credit carryforwards are available indefinitely.
	The future utilization of the Company's net operating loss and research and development credit carryforwards to offset future taxable income may be subject to limitation as a result of ownership changes and restructurings that have occurred previously or that could occur in the future. The Tax Reform Act of 1986 (the Act) limits a company's ability to utilize certain tax credit carryforwards and net operating loss carryforwards in the event of a cumulative change in ownerships in excess of 50% as defined in the Act. The Company has not completed its analysis to determine what, if any, impact the ownership change and restructuring would have on the Company's ability to utilize its net operating loss and research and development credit carryforwards. Until this analysis has been completed, the Company has removed the deferred tax assets for net operating losses of $34.6 million and tax credits of $5.6 million generated through 2012 from its deferred tax asset schedule and has recorded a corresponding decrease to its valuation allowance. When this analysis is finalized, the Company plans to update its unrecognized tax benefits. Due to the existence of the valuation allowance, future changes in the Company's unrecognized tax benefits will not impact the Company's effective tax rate.
	The Company recognizes excess tax benefits associated with the exercise of stock options directly to stockholders equity only when realized. Accordingly, deferred tax assets are not recognized for net operating losses resulting from excess tax benefits. As of December 31, 2013, deferred tax assets do not include approximately $99,000 of these excess tax benefits from employee stock option exercises that are a component of the Company's net operating loss carryforwards. Accordingly, additional paid in capital will increase $99,000 if and when such excess tax benefits are realized. During 2013, no excess tax benefits were realized.
	The impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. There were no unrecognized tax benefits recorded by the Company as of the date of adoption. As a result of the implementation, the Company did not recognize an increase in the liability for unrecognized tax benefits. There are no unrecognized tax benefits included in the consolidated balance sheets that would, if recognized, affect the effective tax rate.
	The Company is subject to taxation in the US and California. The Company is subject to tax examination by tax authorities in those jurisdictions for 2009 and forward. The Company's practice is to recognize interest and/or penalties related to income tax matters as income tax expense. The Company has no accruals for interest or penalties on its accompanying consolidated balance sheets as of December 31, 2013 and 2012, and has not recognized interest or penalties in its consolidated statements of operations and comprehensive loss for all periods presented.

Employee_Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2013
Employee Benefits	'
Employee Benefits	'
	12. Employee Benefits
	The Company has a defined contribution 401(k) plan for all employees. Employees are eligible to participate in the plan beginning on the first day of the month following date of hire. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation. During the years ended December 31, 2013 and 2012, the Company did not make any matching contributions.

Selected_Quarterly_Financial_I

Selected Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2013
Selected Quarterly Financial Information (Unaudited)	'
Selected Quarterly Financial Information (Unaudited)	'
	13. Selected Quarterly Financial Information (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 2013 and 2012 are as follows (in thousands, except per share data):
		First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
	2013:00:00
	Collaborative revenue	$	1,488		$	1,238		$	1,142		$	773
	Operating expenses	$	9,082		$	11,030		$	16,550		$	15,872
	Net loss	$	(9,649	)	$	(9,918	)	$	(15,565	)	$	(15,244	)
	Basic and diluted net loss per common share(1)	$	(5.46	)	$	(0.98	)	$	(0.88	)	$	(0.86	)
	2012:00:00
	Collaborative revenue	$	1,325		$	1,690		$	1,794		$	3,838
	Operating expenses	$	5,223		$	5,040		$	7,798		$	8,296
	Net loss	$	(3,902	)	$	(3,349	)	$	(6,003	)	$	(4,456	)
	Basic and diluted net loss per common share(1)	$	(3.53	)	$	(2.67	)	$	(4.44	)	$	(3.08	)
	-1
	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Subsequent_Events_Unaudited

Subsequent Events (Unaudited)	12 Months Ended
	Dec. 31, 2013
Subsequent Events (Unaudited)	'
Subsequent Events (Unaudited)	'
	14. Subsequent Events (Unaudited)
	Sale of Common Stock.    On January 14, 2014, the Company completed an underwritten public offering of 3,818,000 shares of its common stock at an offering price of $30.75 per share. The Company received net proceeds of approximately $109.9 million, after deducting underwriting discounts, commissions and offering-related expenses of $7.5 million.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Use of Estimates	'
	Use of Estimates
	The Company's consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (US GAAP). The preparation of the Company's consolidated financial statements requires management to make informed estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company's consolidated financial statements and accompanying notes. The most significant estimates in the Company's consolidated financial statements relate to clinical trial accruals and revenue recognition. Although these estimates are based on the Company's knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Segment Reporting	'
	Segment Reporting
	Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment operating primarily in the US.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	The Company classifies time deposits and other investments that are highly liquid and have maturities of 90 days or less at the date of purchase as cash equivalents. The carrying amounts approximate fair value due to the short maturities of these instruments. Cash and cash equivalents include cash in readily available checking and money market accounts, as well as corporate debt securities.
Short-Term Investments	'
	Short-Term Investments
	The Company carries short-term investments classified as available-for-sale at fair value as determined by prices for identical or similar securities at the balance sheet date. Short-term investments consist of both Level 1 and Level 2 financial instruments in the fair value hierarchy. The Company records unrealized gains and losses as a component of other comprehensive loss within the statements of operations and comprehensive loss and as a separate component of stockholders' equity (deficit). Realized gains or losses of available-for-sale securities is determined using the specific identification method and we include net realized gains and losses in interest income.
	At each balance sheet date, the Company assesses available-for-sale securities in an unrealized loss position to determine whether the unrealized loss is other-than-temporary. The Company considers factors including: the significance of the decline in value compared to the cost basis, underlying factors contributing to a decline in the prices of securities in a single asset class, the length of time the market value of the security has been less than its cost basis, the security's relative performance versus its peers, sector or asset class, expected market volatility and the market and economy in general. An impairment loss is recognized at the time the Company determines that a decline in the fair value below its cost basis is other-than-temporary.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The valuation of assets and liabilities are subject to fair value measurements using a three tiered approach and fair value measurement is classified and disclosed by the Company in one of the following three categories:
	Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;
	Level 2: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability;
	Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e. supported by little or no market activity).
	The carrying amounts of all cash equivalents, short-term investments, accounts payable and accrued liabilities are reasonable estimates of their fair value because of the short-term nature of these items.
Concentrations of Credit Risk	'
	Concentrations of Credit Risk
	Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.
Property and Equipment	'
	Property and Equipment
	Property and equipment is carried at cost and depreciation is computed using the straight-line method over the estimated useful lives of the assets (generally three to seven years). The Company amortizes leasehold improvements over the lease term or the useful life of the improvement, whichever is shorter (including any renewal periods that are deemed to be reasonably assured). The Company expenses repair and maintenance costs that do not improve service potential or extend economic life as incurred.
Impairment of Long-Lived Assets	'
	Impairment of Long-Lived Assets
	The Company reviews property and equipment for impairment on an annual basis and whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. An impairment loss would be recognized when estimated future undiscounted cash flows relating to the asset are less than its carrying amount. An impairment loss is measured as the amount by which the carrying amount of an asset exceeds its fair value. While the Company's current and historical operating losses and negative cash flows are possible indicators of impairment, management believes that the future cash flows to be generated by these assets support the carrying value of its long-lived assets and, accordingly, has not recognized any significant impairment losses during the years ended December 31, 2013, 2012 and 2011.
Income Taxes	'
	Income Taxes
	The accounting guidance for uncertainty in income taxes prescribes a recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position.
	The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made.
Revenue Recognition	'
	Revenue Recognition
	The Company enters into arrangements with pharmaceutical and biotechnology partners that may involve multiple deliverables. The Company's arrangements may contain upfront payments, license fees for research and development arrangements, research and development funding and milestone payments under collaborative agreements. Each deliverable in the arrangement is evaluated to determine whether it meets the criteria to be accounted for as a separate unit of accounting or whether it should be combined with other deliverables. Revenue is recognized separately for each unit of accounting when all four of the following criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured.
	Upfront Fees.    When management determines the Company has a single unit of accounting under its collaborative arrangements, upfront fees received for collaborative agreements are recognized ratably over the expected performance period under each respective arrangement. As a result, management makes its best estimate of the period over which the Company expects to fulfill its performance obligations under that agreement. Any amounts received under the agreements in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.
	Milestones.    The Company evaluates all milestones at the beginning of the agreement to determine if they meet the definition of a substantive milestone. Revenue is recognized from milestone payments when earned, provided that (i) the milestone event is substantive in that it can only be achieved based in whole or in part on either the Company's performance or on the occurrence of a specific outcome resulting from the Company's performance and its achievability was not reasonably assured at the inception of the agreement, (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone and (iii) it would result in the receipt of additional payments. A milestone payment is considered substantive if all of the following conditions are met: (i) the milestone payment is non-refundable; (ii) achievement of the milestone was not reasonably assured at the inception of the arrangement; (iii) substantive effort is involved to achieve the milestone; and (iv) the amount of the milestone payments appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone.
	Deferred Revenue.    Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized within the next 12 months are classified as non-current deferred revenue.
Research and Development	'
	Research and Development
	Research and development (R&D) expenses include the costs associated with the Company's R&D activities, including salaries, benefits and occupancy costs. Also included in R&D expenses are third-party costs incurred in conjunction with contract manufacturing for the Company's R&D programs and clinical trials, including the cost of clinical trial drug supply shipped to its clinical study vendors, regulatory expenses and costs incurred by contract research organizations (CROs). R&D costs are expensed as incurred, except when accounting for nonrefundable advance payments for goods or services to be used in future R&D activities. These payments are capitalized at the time of payment and expensed ratably over the period the R&D activity is performed.
Clinical Study Costs and Clinical Trial Accruals	'
	Clinical Study Costs and Clinical Trial Accruals
	The Company accounts for a significant portion of its clinical study costs according to the terms of its contracts with CROs. The financial terms of its CRO contracts may result in payment flows that do not match the periods over which materials or services are provided to us under such contracts. The Company's objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. As part of the process of preparing its financial statements, the Company relies on cost information provided by its CROs (concerning monthly expenses as well as reimbursement for pass through costs). The Company is also required to estimate certain of its expenses resulting from its obligations under its CRO contracts. Accordingly, the Company's clinical trial accrual is dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.
Stock-Based Compensation	'
	Stock-Based Compensation
	The Company accounts for stock-based compensation expense related to stock options granted to employees and members of its board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes options-pricing model, net of estimated forfeitures. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized using the straight-line method. In accordance with the authoritative accounting literature, options subject to both performance and time-based vesting conditions are expensed using an accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), compensation expense is recognized over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition during the earlier vesting periods. The Company accounts for stock options granted to non-employees using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms.
	For performance-based awards to employees (i) the fair value of the award is determined on the grant date, (ii) the Company assesses the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. For performance-based awards to non-employees, no expense is recognized until such time as the milestone event is achieved. Upon achievement, the portion of the milestone subject to immediate vesting is expensed based upon the then fair value of the award. For the portion of the award further subject to time-based vesting restrictions, expense is recorded quarterly, at the then fair value, as the shares vest until such time as performance is complete.
Comprehensive Loss	'
	Comprehensive Loss
	Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources.
Net Loss per Share	'
	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 calculated by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of convertible preferred stock, stock options and warrants. The calculation of the weighted-average number of shares outstanding excludes shares which have been issued upon the early exercise of stock options and are subject to future vesting and unvested restricted stock totaling 0.5 million and 0.9 million shares as of December 31, 2013 and 2012, respectively.
	Basic and diluted net loss per share are equivalent because the Company has incurred a net loss in all periods presented causing any potentially dilutive securities to be anti-dilutive. Potentially dilutive securities totaled 3.8 million, 6.9 million and 5.3 million shares of common stock as of December 31, 2013, 2012 and 2011, respectively.
Reclassification of Prior Period Balances	'
	Reclassification of Prior Period Balances
	Certain reclassifications have been made to prior period amounts to conform to current-year presentation.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board issued an accounting standard update to require reclassification adjustments from other comprehensive income to be presented either in the financial statements or in the notes to the financial statements. This accounting standard became effective for the Company beginning in the first quarter of fiscal 2013, and its adoption did not have any impact on the Company's consolidated financial statements.

ShortTerm_Investments_Tables

Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Short-Term Investments.	'
Schedule of carrying value of available for sale securities classified as short-term investments	'
	The carrying value of available for sale securities classified as short-term investments consisted of the following as (in thousands):
		As of December 31, 2013
		Amortized		Unrealized		Unrealized			Fair Market
		Cost		Gains		Losses			Value
	Commercial paper	$	18,927	$	17	$	—		$	18,944
	Corporate debt securities		26,752		—		(11	)		26,741
	Total	$	45,679	$	17	$	(11	)	$	45,685
Summary of fair value of the Company's investment holdings	'
	The fair value of the Company's investment holdings is summarized in the following table (in thousands):
		As of December 31, 2013
				Fair Value Determined Under
		Total Fair
		Value		(Level 1)		(Level 2)			(Level 3)
	Money market funds	$	8,147	$	8,147	$	—		$	—
	Commercial paper		18,944		—		18,944			—
	Corporate debt securities		37,649		—		37,649			—
	Total	$	64,740	$	8,147	$	56,593			—

Balance_Sheet_Details_Tables

Balance Sheet Details (Tables)	12 Months Ended
	Dec. 31, 2013
Balance Sheet Details	'
Summary of major classes of prepaid expenses and other current assets	'
	The following table summarizes major classes of prepaid expenses and other current assets (in thousands):
		December 31,
		2013			2012
	Prepaid insurance	$	321		$	62
	Interest receivable		277			—
	Prepaid contract research costs		—			435
	Prepaid other		316			212
	Total	$	914		$	709
Summary of major classes of property and equipment	'
	The following table summarizes major classes of property and equipment (in thousands):
				December 31,
		Useful
		life		2013			2012
	Laboratory equipment	3 years		$	2,860		$	2,940
	Computer equipment and software	3 years			150			226
	Leasehold improvements	7 years			854			854
					3,864			4,020
	Less accumulated depreciation and amortization				3,595			3,471
	Property and equipment, net			$	269		$	549
Summary of major classes of accrued liabilities	'
	The following table summarizes major classes of accrued liabilities (in thousands):
		December 31,
		2013			2012
	Accrued clinical trial services	$	3,197		$	1,289
	Accrued royalty payable		550			176
	Repurchase liability for unvested restricted stock awards		108			188
	Other accrued liabilities		3,757			217
	Total	$	7,612		$	1,870

Collaborative_Arrangements_Tab

Collaborative Arrangements (Tables)	12 Months Ended
	Dec. 31, 2013
Collaborative Arrangements	'
Schedule of recognized revenue	'
	The Company recognized revenue under these arrangements as follows (in thousands):
		Year ended December 31,
	Partner	2013		2012		2011
	Ono Pharmaceutical Co., Ltd.	$	4,641	$	6,088	$	212
	Eli Lilly and Company		—		2,480		2,520
	Ortho-McNeil-Janssen Pharmaceuticals		—		79		6,500
	Collaborative revenue	$	4,641	$	8,647	$	9,232

Term_Loan_and_Security_Agreeme1

Term Loan and Security Agreement (Tables)	12 Months Ended
	Dec. 31, 2013
Term Loan and Security Agreement	'
Schedule of future principal payments due under the loan agreement	'
	Future principal payments due under the loan agreement are as follows (in thousands):
	2014	$	735
	2015		1,765
	2016		1,765
	2017		735
	Total future principal payments due under loan agreement	$	5,000

StockBased_Compensation_and_Eq1

Stock-Based Compensation and Equity Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Stock-Based Compensation and Equity Plans	'
Summary of stock option activity	'
	The following table summarizes stock option activity for the year ended December 31, 2013 (share amounts in thousands):
		# Shares			Weighted			Weighted
					Average			Average
					Exercise			Remaining
					Price			Contractual
					per Share			Term (years)
	Outstanding at December 31, 2012		59		$	0.3
	Granted		1,351			15.28
	Exercised		(13	)		0.27
	Outstanding at December 31, 2013		1,397		$	14.78			9.4
	Vested or expected to vest at December 31, 2013		741		$	0.82			6.5
	Exercisable at December 31, 2013		81		$	6.18			8.4
Schedule of weighted-average assumptions underlying the calculation of grant date fair value	'
		Year ended December 31,
		2013			2012			2011
	Risk free interest rate		1.4	%		1.1	%		2.2	%
	Expected term (years)		6.1			6			6.1
	Expected volatility		105.9	%		94.2	%		87.7	%
	Expected dividend yield		0	%		0	%		0	%
Summary of share-based compensation expense for all awards granted	'
	The following table summarizes share-based compensation expense for all awards granted (in thousands):
		Year ended December 31,
		2013			2012			2011
	Research and development	$	1,360		$	192		$	33
	General and administrative		1,609			28			29
	Total share-based compensation expense	$	2,969		$	220		$	62

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Taxes	'
Schedule of reconciliation of the expected statutory federal income tax provision to the actual income tax provision	'
	The following is a reconciliation of the expected statutory federal income tax provision to the actual income tax provision (in thousands):
		Year ended December 31,
		2013			2012			2011
	Expected income tax benefit at federal statutory tax rate	$	(16,429	)	$	(6,021	)	$	(2,077	)
	State income taxes, net of federal benefit		(2,694	)		(1,019	)		(320	)
	Permanent items		558			82			277
	Research credits		(2,393	)		(477	)		(1,096	)
	Removal of net operating losses and research and development credits		20,527			6,774			3,014
	Change in valuation allowance		431			661			202
	Income tax (benefit) expense	$	—		$	—		$	—
Summary of significant components of deferred tax assets	'
	The following table summarizes the significant components of deferred tax assets (in thousands):
		December 31,
		2013			2012
	Deferred tax assets:
	Depreciation and amortization	$	499		$	630
	Deferred revenue		279			564
	Stock options		543			—
	Accrued expenses and reserves		705			402
	Total deferred tax assets		2,026			1,596
	Less: Valuation allowance		2,026			1,596
	Net deferred tax assets	$	—		$	—

Selected_Quarterly_Financial_I1

Selected Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2013
Selected Quarterly Financial Information (Unaudited)	'
Summary of selected quarterly financial data	'
	Summarized quarterly data for 2013 and 2012 are as follows (in thousands, except per share data):
		First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
	2013:00:00
	Collaborative revenue	$	1,488		$	1,238		$	1,142		$	773
	Operating expenses	$	9,082		$	11,030		$	16,550		$	15,872
	Net loss	$	(9,649	)	$	(9,918	)	$	(15,565	)	$	(15,244	)
	Basic and diluted net loss per common share(1)	$	(5.46	)	$	(0.98	)	$	(0.88	)	$	(0.86	)
	2012:00:00
	Collaborative revenue	$	1,325		$	1,690		$	1,794		$	3,838
	Operating expenses	$	5,223		$	5,040		$	7,798		$	8,296
	Net loss	$	(3,902	)	$	(3,349	)	$	(6,003	)	$	(4,456	)
	Basic and diluted net loss per common share(1)	$	(3.53	)	$	(2.67	)	$	(4.44	)	$	(3.08	)
	-1
	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Description_of_Business_Detail

Description of Business (Details) (USD $)	1 Months Ended	12 Months Ended		0 Months Ended
	31-May-13	Dec. 31, 2013	Dec. 31, 2012	Jan. 14, 2014
				Subsequent event
Description of business	'	'	'	'
Accumulated deficit	'	($95,909,000)	($47,589,000)	'
Cash, cash equivalents and short-term investments	'	69,500,000	'	'
Net proceeds received	$75,000,000	$75,009,000	'	$109,900,000

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2013
	item
Segment Reporting	'
Number of operating segments	1
Minimum	'
Property and Equipment	'
Estimated useful lives	'3 years
Maximum	'
Property and Equipment	'
Estimated useful lives	'7 years

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details 2)	12 Months Ended
	Dec. 31, 2013
	item
Revenue Recognition	'
Number of criteria for considering revenue recognition separately for each element	4

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Details 3)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of Significant Accounting Policies	'	'	'
Shares excluded from the weighted-average number of shares outstanding, which have been issued upon the early exercise of stock options and are subject to future vesting and unvested restricted stock	0.5	0.9	'
Potentially dilutive securities (in shares)	3.8	6.9	5.3

ShortTerm_Investments_Details

Short-Term Investments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Short-Term Investments	'
Other-than-temporary decline in the value of available-for-sale investment securities	$0
Maximum	'
Short-Term Investments	'
Maturity date for available-for-sale investment securities	'1 year
Cash equivalents	'
Short-Term Investments	'
Fair Market Value	19,100
Short-term investments	'
Short-Term Investments	'
Amortized Cost	45,679
Unrealized Gains	17
Unrealized Losses	-11
Fair Market Value	45,685
Short-term investments | Commercial paper	'
Short-Term Investments	'
Amortized Cost	18,927
Unrealized Gains	17
Fair Market Value	18,944
Short-term investments | Corporate debt securities	'
Short-Term Investments	'
Amortized Cost	26,752
Unrealized Losses	-11
Fair Market Value	$26,741

ShortTerm_Investments_Details_

Short-Term Investments (Details 2) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Total Fair Value	'
Fair value of investment holdings	'
Fair value of investment holdings	$64,740
Total Fair Value | Money market funds	'
Fair value of investment holdings	'
Fair value of investment holdings	8,147
Total Fair Value | Commercial paper	'
Fair value of investment holdings	'
Fair value of investment holdings	18,944
Total Fair Value | Corporate debt securities	'
Fair value of investment holdings	'
Fair value of investment holdings	37,649
Level 1	'
Fair value of investment holdings	'
Fair value of investment holdings	8,147
Level 1 | Money market funds	'
Fair value of investment holdings	'
Fair value of investment holdings	8,147
Level 2	'
Fair value of investment holdings	'
Fair value of investment holdings	56,593
Level 2 | Commercial paper	'
Fair value of investment holdings	'
Fair value of investment holdings	18,944
Level 2 | Corporate debt securities	'
Fair value of investment holdings	'
Fair value of investment holdings	$37,649

Balance_Sheet_Details_Details

Balance Sheet Details (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Prepaid Expenses and Other Current Assets	'	'
Prepaid insurance	$321	$62
Interest receivable	277	'
Prepaid contract research costs	'	435
Prepaid other	316	212
Total	914	709
Property and equipment	'	'
Property and equipment, gross	3,864	4,020
Less accumulated depreciation and amortization	3,595	3,471
Property and equipment, net	269	549
Accrued Expenses	'	'
Accrued clinical trial services	3,197	1,289
Accrued royalty payable	550	176
Repurchase liability for unvested restricted stock awards	108	188
Other accrued liabilities	3,757	217
Total	7,612	1,870
Laboratory equipment	'	'
Property and equipment	'	'
Useful life	'3 years	'
Property and equipment, gross	2,860	2,940
Computer equipment and software	'	'
Property and equipment	'	'
Useful life	'3 years	'
Property and equipment, gross	150	226
Leasehold improvements	'	'
Property and equipment	'	'
Useful life	'7 years	'
Property and equipment, gross	$854	$854

Collaborative_Arrangements_Det

Collaborative Arrangements (Details) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 07, 2011

Feb. 28, 2011

Dec. 31, 2012

Dec. 31, 2011

Ono Pharmaceutical Co., Ltd.

Ono Pharmaceutical Co., Ltd.

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Co-exclusive collaboration agreement

Maximum

Ono Pharmaceutical Co., Ltd.

Ono Pharmaceutical Co., Ltd.

Ono Pharmaceutical Co., Ltd.

Ono Pharmaceutical Co., Ltd.

Eli Lilly and Company

Eli Lilly and Company

Eli Lilly and Company

Eli Lilly and Company

Eli Lilly and Company

Ortho-McNeil-Janssen Pharmaceuticals

Ortho-McNeil-Janssen Pharmaceuticals

Ortho-McNeil-Janssen Pharmaceuticals

Ortho-McNeil-Janssen Pharmaceuticals

item

item

Collaborative arrangements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborative revenue

$773,000

$1,142,000

$1,238,000

$1,488,000

$3,838,000

$1,794,000

$1,690,000

$1,325,000

$4,641,000

$8,647,000

$9,232,000

'

'

$4,641,000

$8,647,000

$9,232,000

'

$4,641,000

$6,088,000

$212,000

'

'

'

$2,480,000

$2,520,000

'

'

$79,000

$6,500,000

Period of the collaboration agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2 years

'

'

'

'

'

'

'

Upfront, non-refundable fee received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,500,000

'

'

'

5,000,000

'

'

'

'

2,500,000

4,000,000

'

'

Number of units of accounting

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1

'

'

'

'

'

1

'

'

'

'

'

'

Research and development support payments recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,700,000

2,600,000

100,000

'

'

'

'

'

'

'

'

'

Upfront license and collaborative research termination fees

'

'

'

'

'

'

'

'

'

'

'

3,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Technology transfer milestone payments

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Milestone payments, which met all criteria necessary for concluding the milestones to be substantive, received and recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

300,000

2,000,000

0

'

'

'

'

'

'

'

'

'

Research milestone payments based on completion of certain research activities

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Development milestone payments based solely upon Ono's performance

'

'

'

'

'

'

'

'

'

'

'

'

$13,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Term_Loan_and_Security_Agreeme2

Term Loan and Security Agreement (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2013	Apr. 19, 2013	Apr. 19, 2013	Dec. 31, 2013
			Credit and security agreement	Credit and security agreement
			item
Term loan and security agreement	'	'	'	'
Maximum borrowing capacity	'	'	$30,000,000	$15,000,000
Number of tranches in which loan issuable	'	'	3	'
Maximum borrowing capacity per tranche	'	'	10,000,000	'
Amount drawn	'	'	'	5,000,000
Remaining borrowing capacity	'	'	'	10,000,000
Interest rate (as a percent)	'	'	8.25%	'
Principal and interest period	'	'	'34 months	'
Debt discount	'	200,000	'	'
Exit fee obligation	350,000	'	'	'
Prepayment fee percentage	'	'	3.00%	'
Prepayment fee percentage after August 18, 2014	'	'	2.00%	'
Prepayment fee percentage after December 18, 2015	'	'	1.00%	'
Future principal payments due under the loan agreement	'	'	'	'
2014	735,000	'	'	'
2015	1,765,000	'	'	'
2016	1,765,000	'	'	'
2017	735,000	'	'	'
Total future principal payments due under loan agreement	$5,000,000	'	'	'

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Apr. 30, 2009

Apr. 30, 2009

Jun. 30, 2009

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jun. 30, 2009

S1P1R Modulators License Agreement

S1P1R Modulators License Agreement

S1P1R Modulators License Agreement

S1P1R Modulators License Agreement

S1P1R Modulators License Agreement

Technology Platform License Agreement

Technology Platform License Agreement

Technology Platform License Agreement

Technology Platform License Agreement

Technology Platform License Agreement

TSRI

TSRI

TSRI

TSRI

TSRI

TSRI

TSRI

TSRI

TSRI

TSRI

Minimum

Maximum

Maximum

item

Commitments and contingencies

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of royalties payable on annual net sales of Licensed Product

'

'

'

'

'

1.50%

2.00%

'

'

'

'

'

Percentage of royalties payable on annual net sales of Non-Patent Product

'

'

'

'

'

0.75%

1.00%

'

'

'

'

'

Number of generic versions of Non-Patent Product commercially sold

'

'

'

'

'

1

'

'

'

'

'

'

Product development milestone payments

'

'

'

'

'

'

$4,400,000

'

'

'

'

$1,000,000

Consideration paid under the agreement

'

'

25,000

10,000

10,000

'

'

'

200,000

500,000

400,000

'

Accrued royalty payable

550,000

176,000

300,000

'

'

'

'

'

200,000

'

'

'

Payment of ATI as a percentage of the first $100 million of cumulative ATI

'

'

'

'

'

'

'

7.50%

'

'

'

'

Amount of the first cumulative ATI for calculating the payments percentage of ATI

'

'

'

'

'

'

'

100,000,000

'

'

'

'

Amount of ATI on the first $2.5 million of cumulative ATI

'

'

'

'

'

'

'

0

'

'

'

'

Amount of the first cumulative ATI on which no ATI payments shall be due

'

'

'

'

'

'

'

2,500,000

'

'

'

'

Threshold amount of cumulative ATI for determination of reduced percentage for the payments of ATI

'

'

'

'

'

'

'

$100,000,000

'

'

'

'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details 2) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	item
Operating Lease	'	'	'
Number of options available for extension of lease term	2	'	'
Extended term of operating lease	'3 years	'	'
Amount of letter of credit maintained	$0.10	'	'
Rent expense	0.9	0.8	0.5
Remaining future minimum commitments under the facility lease	0.5	'	'
Maximum	'	'	'
Other Commitments	'	'	'
Long-term contractual obligations	$7.70	'	'

Convertible_Preferred_Stock_De

Convertible Preferred Stock (Details) (USD $)	12 Months Ended	0 Months Ended	7 Months Ended	12 Months Ended		1 Months Ended		2 Months Ended	12 Months Ended
	Dec. 31, 2013	14-May-13	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013	Feb. 28, 2013	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
		Convertible preferred stock	Series A	Series A	Series A	Series B	Series B	Series B	Series B	Series B
Convertible Preferred Stock	'	'	'	'	'	'	'	'	'	'
Shares Authorized	'	'	'	0	39,376,000	'	'	'	0	48,544,000
Aggregate shares of preferred stock issued	'	'	12,412,000	'	'	8,238,000	12,358,000	12,358,000	'	'
Issue price (in dollars per share)	'	'	$0.70	'	'	$1.03	$1.03	$1.03	'	'
Net cash proceeds from issuance	'	'	$8,700,000	'	'	$8,500,000	$12,700,000	$12,600,000	'	'
Deemed dividend	$2,056,000	'	'	'	'	$2,100,000	'	'	'	'
Outstanding shares of convertible preferred stock	'	72,330,000	'	0	39,376,000	'	'	'	0	12,358,000
Number of shares of common stock issued against conversion of preferred stock	'	9,644,000	'	-39,376,000	'	'	'	'	-32,954,000	'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended
	Apr. 25, 2013	31-May-13	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
					Restricted common stock	Restricted common stock	Option awards	Option awards	Option awards
						Time-Based Awards
Preferred Stock	'	'	'	'	'	'	'	'	'
Authorized shares of undesignated preferred stock	'	10,000,000	10,000,000	0	'	'	'	'	'
Common Stock	'	'	'	'	'	'	'	'	'
Reverse stock split ratio	7.5	'	'	'	'	'	'	'	'
Vesting period	'	'	'	'	'	'2 years	'	'	'
Shares subject to repurchase	'	'	'	'	163,000	'	'	'	'
Options for the purchase of shares of common stock (net of repurchased shares) exercised	'	'	'	'	'	'	982,000	'	'
Options unvested and subject to repurchase (in shares)	'	'	'	'	'	'	307,000	'	'
Shares repurchased	'	'	'	'	'	'	123	0	7,222
Shares of common stock sold in the IPO	'	5,933,277	'	'	'	'	'	'	'
Share price (in dollars per share)	'	$14	'	'	'	'	'	'	'
Net proceeds received	'	$75,000,000	$75,009,000	'	'	'	'	'	'
Underwriting discounts, commissions and offering-related transaction costs	'	$8,100,000	'	'	'	'	'	'	'

StockBased_Compensation_and_Eq2

Stock-Based Compensation and Equity Plans (Details) (2013 Plan)	12 Months Ended
	Dec. 31, 2013	Jan. 01, 2014
2013 Stock Incentive Plan	'	'
Expiration term of awards	'10 years	'
Shares of common stock available for future grant	1,146,600	734,000
Automatic annual increase in number of shares that may be issued under plan as percentage of outstanding shares	4.00%	'
Performance-based Awards	'	'
2013 Stock Incentive Plan	'	'
Vesting percentage upon achievement of a milestone event	25.00%	'
Vesting period	'36 months	'
Time-Based Awards	'	'
2013 Stock Incentive Plan	'	'
Vesting period	'4 years	'

StockBased_Compensation_and_Eq3

Stock-Based Compensation and Equity Plans (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Jan. 01, 2014
		Stock options	Stock options	Stock options	2013 employee stock purchase plan	2013 employee stock purchase plan
Shares	'	'	'	'	'	'
Outstanding at the beginning of the period (in shares)	'	59,000	'	'	'	'
Granted (in shares)	'	1,351,000	'	'	'	'
Exercised (in shares)	'	-13,000	'	'	'	'
Outstanding at the end of the period (in shares)	'	1,397,000	59,000	'	'	'
Vested or expected to vest at the end of the period (in shares)	'	741,000	'	'	'	'
Exercisable at the end of the period (in shares)	'	81,000	'	'	'	'
Weighted Average Exercise Price per Share	'	'	'	'	'	'
Outstanding at the beginning of the period (in dollars per share)	'	$0.30	'	'	'	'
Granted (in dollars per share)	'	$15.28	'	'	'	'
Exercised (in dollars per share)	'	$0.27	'	'	'	'
Outstanding at the end of the period (in dollars per share)	'	$14.78	$0.30	'	'	'
Vested or expected to vest at the end of the period (in dollars per share)	'	$0.82	'	'	'	'
Exercisable at the end of the period (in dollars per share)	'	$6.18	'	'	'	'
Weighted Average Contractual Remaining Term	'	'	'	'	'	'
Outstanding at the end of the period	'	'9 years 4 months 24 days	'	'	'	'
Vested or expected to vest at the end of the period	'	'6 years 6 months	'	'	'	'
Exercisable at the end of the period	'	'8 years 4 months 24 days	'	'	'	'
Vested or expected to vest, additional information	'	'	'	'	'	'
Options early exercised included in vested or expected to vest (in shares)	'	307,000	'	'	'	'
Aggregate Intrinsic Value	'	'	'	'	'	'
Aggregate intrinsic value of options outstanding and exercisable (in dollars per share)	'	$28.99	'	'	'	'
Aggregate intrinsic value of options outstanding (in dollars)	'	$19,900,000	'	'	'	'
Aggregate intrinsic value of options outstanding and exercisable (in dollars)	'	19,900,000	'	'	'	'
Intrinsic value of exercised stock options (in dollars)	'	300,000	24,000	0	'	'
Weighted-average assumptions underlying the calculation of grant date fair value	'	'	'	'	'	'
Risk free interest rate (as a percent)	'	1.40%	1.10%	2.20%	'	'
Expected term	'	'6 years 1 month 6 days	'6 years	'6 years 1 month 6 days	'	'
Expected volatility (as a percent)	'	105.90%	94.20%	87.70%	'	'
Expected dividend yield (as a percent)	'	0.00%	0.00%	0.00%	'	'
Forfeitures as a percentage of total grants (as a percent)	0.26%	'	'	'	'	'
Unrecognized compensation expense and weighted-average period of recognition	'	'	'	'	'	'
Weighted average grant date fair value of options granted (in dollars per share)	'	$15.28	$0.30	$0.23	'	'
Unrecognized compensation expense related to non-vested stock options (in dollars)	'	$16,100,000	'	'	'	'
Weighted-average period over which unrecognized compensation expense is to be recognized	'	'3 years 7 months 6 days	'	'	'	'
Additional disclosures	'	'	'	'	'	'
Shares of common stock reserved for future issuance	'	'	'	'	160,000	'
Automatic annual increase in number of shares that may be issued under plan as percentage of outstanding shares	'	'	'	'	1.00%	'
Shares of common stock available for future issuance	'	'	'	'	'	183,000

StockBased_Compensation_and_Eq4

Stock-Based Compensation and Equity Plans (Details 3) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based compensation expense	'	'	'
Total share-based compensation expense	$2,969	$220	$62
Research and development	'	'	'
Share-based compensation expense	'	'	'
Total share-based compensation expense	1,360	192	33
General and administrative	'	'	'
Share-based compensation expense	'	'	'
Total share-based compensation expense	$1,609	$28	$29

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of the expected statutory federal income tax provision to the actual income tax provision	'	'	'
Expected income tax benefit at federal statutory tax rate	($16,429,000)	($6,021,000)	($2,077,000)
State income taxes, net of federal benefit	-2,694,000	-1,019,000	-320,000
Permanent items	558,000	82,000	277,000
Research credits	-2,393,000	-477,000	-1,096,000
Removal of net operating losses and research and development credits	20,527,000	6,774,000	3,014,000
Change in valuation allowance	431,000	661,000	202,000
Deferred tax assets:	'	'	'
Depreciation and amortization	499,000	630,000	'
Deferred revenue	279,000	564,000	'
Stock options	543,000	'	'
Accrued expenses and reserves	705,000	402,000	'
Total deferred tax assets	2,026,000	1,596,000	'
Less: Valuation allowance	2,026,000	1,596,000	'
Additional disclosures	'	'	'
Removal of deferred tax assets for net operating losses	'	34,600,000	'
Removal of deferred tax assets for tax credits	'	5,600,000	'
Excess tax benefits that are a component of the Company's net operating loss carryforwards	99,000	'	'
Excess tax benefits realized	0	'	'
Increase in additional paid in capital if and when excess tax benefits are realized	99,000	'	'
Federal	'	'	'
Net operating loss carryforwards	'	'	'
Net operating loss carryforwards	87,100,000	'	'
California	'	'	'
Net operating loss carryforwards	'	'	'
Net operating loss carryforwards	$87,200,000	'	'

Income_Taxes_Details_2

Income Taxes (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Uncertain income tax position	'	'
Unrecognized tax benefits	$0	'
Unrecognized tax benefits included in the consolidated balance sheets that would, if recognized, affect the effective tax rate	0	'
Accruals for interest or penalties	0	0
Federal | Research and development tax credit	'	'
Tax credit carryforwards	'	'
Tax credit carryforwards	4	'
California | Research and development tax credit	'	'
Tax credit carryforwards	'	'
Tax credit carryforwards	$2.50	'

Selected_Quarterly_Financial_I2

Selected Quarterly Financial Information (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Selected Quarterly Financial Information (Unaudited)	'	'	'	'	'	'	'	'	'	'	'
Collaborative revenue	$773	$1,142	$1,238	$1,488	$3,838	$1,794	$1,690	$1,325	$4,641	$8,647	$9,232
Operating expenses	15,872	16,550	11,030	9,082	8,296	7,798	5,040	5,223	52,534	26,357	15,559
Net loss attributable to common stockholders	($15,244)	($15,565)	($9,918)	($9,649)	($4,456)	($6,003)	($3,349)	($3,902)	($50,376)	($17,710)	($6,110)
Basic and diluted net loss per common share (in dollars per share)	($0.86)	($0.88)	($0.98)	($5.46)	($3.08)	($4.44)	($2.67)	($3.53)	($4.23)	($13.73)	($7.72)

Subsequent_Events_Unaudited_De

Subsequent Events (Unaudited) (Details) (USD $)	1 Months Ended	12 Months Ended	0 Months Ended
	31-May-13	Dec. 31, 2013	Jan. 14, 2014
			Subsequent event
Subsequent events	'	'	'
Shares of common stock sold in the offering	5,933,277	'	3,818,000
Share price (in dollars per share)	$14	'	$30.75
Net proceeds received	$75,000,000	$75,009,000	$109,900,000
Underwriting discounts, commissions and offering-related expenses	$8,100,000	'	$7,500,000