Ultragenyx Pharmaceutical (RARE) 10-Q 11 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 06, 2014
Document And Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'RARE	'
Entity Registrant Name	'Ultragenyx Pharmaceutical Inc.	'
Entity Central Index Key	'0001515673	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	31,703,990

CONDENSED_BALANCE_SHEETS

CONDENSED BALANCE SHEETS (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$17,452	$7,427
Short-term investments	135,819	45,950
Prepaid expenses and other current assets	4,945	1,848
Total current assets	158,216	55,225
Property and equipment, net	2,497	1,325
Restricted cash	744	451
Other assets	1,129	2,648
Total assets	162,586	59,649
Liabilities, Convertible Preferred Stock and Stockholders’ Equity (Deficit)	'	'
Accounts payable	3,590	1,437
Accrued liabilities	5,278	4,406
Deferred rent—current portion	75	78
Total current liabilities	8,943	5,921
Convertible preferred stock warrant liability	'	3,419
Other liabilities	560	200
Total liabilities	9,503	9,540
Commitments and contingencies (Note 10)	'	'
Stockholders’ equity (deficit):	'	'
Preferred stock, par value of $0.001 per share—25,000,000 shares authorized; nil outstanding as of June 30, 2014 and December 31, 2013	'	'
Common stock, par value of $0.001 per share—250,000,000 shares authorized; 30,059,288 and 3,766,289 shares issued and outstanding as of June 30, 2014 and December 31, 2013	30	4
Additional paid-in capital	259,555	'
Accumulated other comprehensive income (loss)	-48	11
Accumulated deficit	-106,454	-74,836
Total stockholders’ equity (deficit)	153,083	-74,821
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	162,586	59,649
Series A Convertible Preferred Stock | Redeemable Convertible Preferred Stock	'	'
Liabilities, Convertible Preferred Stock and Stockholders’ Equity (Deficit)	'	'
Convertible preferred stock	'	51,001
Series B Convertible Preferred Stock | Convertible Preferred Stock	'	'
Liabilities, Convertible Preferred Stock and Stockholders’ Equity (Deficit)	'	'
Convertible preferred stock	'	$73,929

CONDENSED_BALANCE_SHEETS_Paren

CONDENSED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	30,059,288	3,766,289
Common stock, shares outstanding	30,059,288	3,766,289
Series A Convertible Preferred Stock | Redeemable Convertible Preferred Stock	'	'
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	0	35,377,566
Convertible preferred stock, shares issued	0	34,349,894
Convertible preferred stock, shares outstanding	0	34,349,894
Series B Convertible Preferred Stock | Convertible Preferred Stock	'	'
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	0	27,081,680
Convertible preferred stock, shares issued	0	27,081,680
Convertible preferred stock, shares outstanding	0	27,081,680

CONDENSED_STATEMENTS_OF_OPERAT

CONDENSED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating expenses:	'	'	'	'
Research and development	$11,239	$7,199	$19,592	$12,863
General and administrative	2,422	1,048	4,408	2,131
Total operating expenses	13,661	8,247	24,000	14,994
Loss from operations	-13,661	-8,247	-24,000	-14,994
Other income (expense), net:	'	'	'	'
Interest income	149	63	242	89
Other expense, net	-73	-406	-3,457	-420
Total other income (expense), net	76	-343	-3,215	-331
Net loss	-13,585	-8,590	-27,215	-15,325
Net loss attributable to common stockholders	($13,585)	($10,829)	($32,023)	($19,034)
Net loss per share attributable to common stockholders, basic and diluted	($0.45)	($3.32)	($1.25)	($6.19)
Shares used in computing net loss per share attributable to common stockholders, basic and diluted	30,055,943	3,257,806	25,697,407	3,076,907

CONDENSED_STATEMENTS_OF_COMPRE

CONDENSED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net loss	($13,585)	($8,590)	($27,215)	($15,325)
Other comprehensive income:	'	'	'	'
Unrealized loss on available-for-sale securities	-2	-66	-59	-77
Total comprehensive loss	($13,587)	($8,656)	($27,274)	($15,402)

CONDENSED_STATEMENTS_OF_CASH_F

CONDENSED STATEMENTS OF CASH FLOWS (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities:	'	'
Net loss	($27,215,000)	($15,325,000)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	278,000	227,000
Amortization of premium (discount) on investment securities	1,396,000	365,000
Stock-based compensation	1,741,000	376,000
Revaluation of convertible preferred stock warrant liability	3,324,000	372,000
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other current assets	-3,097,000	-1,288,000
Other assets	1,519,000	-129,000
Accounts payable	1,960,000	886,000
Accrued liabilities and other liabilities	1,229,000	-164,000
Net cash used in operating activities	-18,865,000	-14,680,000
Investing activities:	'	'
Purchase of property and equipment	-1,257,000	-75,000
Purchase of investments	-129,298,000	-57,935,000
Proceeds from maturities of investments	37,974,000	'
Increase in restricted cash	-293,000	-50,000
Net cash used in investing activities	-92,874,000	-58,060,000
Financing activities:	'	'
Net proceeds from issuance of common stock	126,110,000	57,000
Payment of preferred stock dividend	-4,346,000	'
Net cash provided by financing activities	121,764,000	57,000
Net increase (decrease) in cash and cash equivalents	10,025,000	-72,683,000
Cash and cash equivalents at beginning of period	7,427,000	86,190,000
Cash and cash equivalents at end of period	17,452,000	13,507,000
Supplemental disclosures of non-cash investing and financing information:	'	'
Reclassification of warrant liability to equity upon conversion to common stock warrants	6,743,000	'
Series A and Series B	'	'
Supplemental disclosures of non-cash investing and financing information:	'	'
Conversion of Series A and Series B preferred stock to common stock	$129,360,000	'

Organization

Organization	6 Months Ended
	Jun. 30, 2014
Organization	'
	1	Organization
	Ultragenyx Pharmaceutical Inc. (the Company) is a clinical-stage biotechnology company incorporated in California on April 22, 2010. The Company subsequently reincorporated in the state of Delaware in June 2011.
	The Company is focused on the identification, acquisition, development, and commercialization of novel products for the treatment of rare and ultra-rare diseases, with a focus on serious, debilitating genetic diseases. The Company is currently conducting a Phase 2 extension study of sialic acid, extended release (SA-ER) in patients with hereditary inclusion body myopathy (HIBM), a progressive muscle-wasting disorder; a Phase 1/2 study of recombinant human beta-glucuronidase (rhGUS) in patients with mucopolysaccharidosis 7, or MPS 7, a rare lysosomal storage disease; a Phase 2 clinical study for triheptanoin for the treatment of patients with glucose transporter type-1 deficiency syndrome (Glut1 DS), a brain energy deficiency; a Phase 2 clinical study of triheptanoin, in patients severely affected by long-chain fatty acid oxidation disorders (LC-FAOD), a genetic disorder in which the body is unable to convert long chain fatty acids into energy; and a Phase 2 study of KRN23, an antibody targeting fibroblast growth factor 23, or FGF23, in pediatric patients with X-linked hypophosphatemia (XLH), a rare genetic disease that impairs bone growth.
	On January 30, 2014, the Company’s registration statements on Form S-1 (File Nos. 333-192244 and 333-193675) relating to its initial public offering (IPO) of its common stock were declared effective by the Securities and Exchange Commission (SEC). The shares began trading on The NASDAQ Global Select Market on January 31, 2014. The public offering price of the shares sold in the offering was $21.00 per share. The IPO closed on February 5, 2014 and included 6,624,423 shares of common stock, which included 864,054 shares of common stock issued pursuant to the over-allotment option granted to the underwriters. The Company received total proceeds from the offering of $129.4 million, net of underwriting discounts and commissions of $9.7 million. After deducting offering expenses of approximately $3.3 million and a cash dividend of $4.3 million, which was paid to the preferred stockholders on the closing date, net proceeds were approximately $121.7 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 19,598,486 shares of common stock and the Series A convertible preferred stock warrants were converted into warrants to purchase common stock.
	Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on February 5, 2014, the number of shares of capital stock the Company is authorized to issue was increased to 275,000,000 shares, of which 250,000,000 shares are common stock and 25,000,000 shares are preferred stock. Both the common stock and preferred stock have a par value of $0.001 per share. There are no shares of preferred stock outstanding at June 30, 2014.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
Summary of Significant Accounting Policies	'
	2	Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. general accepted accounting principles (“U.S. GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. The unaudited interim consolidated financial statements have been prepared on the same basis as the annual financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation. These financial statements should be read in conjunction with the audited financial statements and notes thereto for the preceding fiscal year contained in the Company’s Annual Report on Form 10-K filed on March 24, 2014 with the SEC.
	The results of operations for the three and six months ended June 30, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014. The condensed balance sheet as of December 31, 2013 has been derived from audited financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements.
	Reverse Stock Split
	In January 2014, the Company’s board of directors and its stockholders approved an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock on a 1-for-3.1345 basis (the “Reverse Stock Split”). The par values and the authorized shares of the common and convertible preferred stock were not adjusted as a result of the Reverse Stock Split, nor were the outstanding shares of preferred stock. All issued and outstanding common stock and related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. A proportional adjustment to the conversion ratio for each series of convertible preferred stock was also effected in connection with the Reverse Stock Split. The Reverse Stock Split was effected on January 17, 2014.
	Use of Estimates
	The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical study accruals, fair value of assets and liabilities, convertible preferred stock and related warrants, common stock, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts.
	Short-Term Investments
	All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and were reported as a component of comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest income and other expense, respectively. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest income.
	Deferred Offering Costs
	Deferred offering costs, which primarily consist of direct incremental accounting, legal and printing fees relating to the IPO and to the Company’s underwritten public offering in July 2014, were initially capitalized. IPO deferred offering costs of $3.3 million were subsequently offset against IPO proceeds upon the completion of the IPO in February 2014. Underwritten public offering costs of $444,000 were subsequently offset against offering proceeds on completion of our underwritten public offering in July 2014. As of June 30, 2014 and December 31, 2013, deferred offering costs of $316,000 and $2.3 million, respectively, were capitalized and included in prepaid and other current assets on the balance sheet.
	Concentration of Credit Risk and Other Risks and Uncertainties
	Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents, and marketable securities. The Company’s cash, cash equivalents, and short-term investments are held by financial institutions that management believes are of high credit quality. The Company’s investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as U.S. government obligations, money market instruments and funds, corporate bonds, and asset-backed securities and places restrictions on maturities and concentrations by type and issuer. Such deposits may, at times, exceed federally insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents and its accounts are monitored by management to mitigate risk. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and corporate bond issuers to the extent recorded in the balance sheets.
	Income Taxes
	The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.
	The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.
	Net Loss per Share Attributable to Common Stockholders
	Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. The net loss attributable to common stockholders is calculated by adjusting the net loss of the Company for the accretion on the Series A convertible preferred stock and cumulative dividends paid on Series A and B convertible preferred stock. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since the effects of potentially dilutive securities are antidilutive.
	Recently Issued Accounting Pronouncements
	In June 2014, the Financial Accounting Standards Board issued Accounting Standards Update 2014-10, Development Stage Enterprises: Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation (ASU 2014-10). ASU 2014-10 removes the definition of a development stage entity from the Master Glossary of the Accounting Standards Codification, thereby removing the financial reporting distinction between development stage entities and other reporting entities from U.S. GAAP. ASU 2014-10 also eliminates the requirements for development stage entities to (1) present inception-to-date information in the statements of income, cash flows, and shareholder equity, (2) label the financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged, and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. The amendments also clarify that the guidance in Topic 275, Risks and Uncertainties, is applicable to entities that have not commenced planned principal operations. The amendments in ASU 2014-10 will be effective retrospectively except for the clarification to Topic 275, which shall be applied prospectively for annual reporting periods beginning after December 15, 2014, and interim periods therein. Early application of each of the amendments is permitted for any annual reporting period or interim period for which the entity’s financial statements have not yet been issued. The Company elected to early adopt the provisions of ASU 2014-10 in the second quarter of 2014, as reflected in this Quarterly Report.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
Fair Value Measurements	'
	3	Fair Value Measurements
	Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:
	Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;
	Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and
	Level 3—Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.
	The following tables set forth the fair value of the Company’s financial assets and liabilities remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands):
		30-Jun-14
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	6,753		$	—	$	—	$	6,753
	Commercial paper		—			7,988		—		7,988
	Corporate bonds		—			125,840		—		125,840
	U.S. Government securities		—			3,002		—		3,002
	Total financial assets	$	6,753		$	136,830	$	—	$	143,583
		December 31, 2013
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	6,847		$	—	$	—	$	6,847
	Commercial paper		—			1,000		—		1,000
	Corporate bonds		—			44,950		—		44,950
	Total financial assets	$	6,847		$	45,950	$	—	$	52,797
	Financial Liabilities:
	Convertible preferred stock warrant liability	$	—		$	—	$	3,419	$	3,419
	Total financial liabilities	$	—		$	—	$	3,419	$	3,419
	The convertible preferred stock warrant liability was classified as a Level 3 liability. As of December 31, 2013, the Company determined the estimated fair value of the warrants using an option-pricing method to allocate the equity value of the Company to the warrants based on the Company’s capital structure. The equity value was estimated using the back-solve method, whereby the equity value was derived from a recent transaction involving the Company’s own securities. The key inputs used to determine value of the warrants was an estimated fair value of the Company’s common stock of $12.14 per share, expected volatility of 70%, the expected time to liquidity event of 0.43 years and risk-free interest rate of 0.11%. The significant unobservable input used in the fair value measurement of the convertible preferred stock warrant liability was the equity value of the Company. Generally, increases (decreases) in the equity value of the Company would result in a directionally similar impact to the fair value measurement of the preferred stock warrant liability.
	As of January 30, 2014, the Company determined the estimated fair value of the warrants using the Black-Scholes option-pricing model. Inputs used to determine the fair value included the value of the Company’s common stock upon closing of the IPO of $21.00, the remaining contractual term of the warrants of 7.0 years, risk-free interest rate of 2.19% and expected volatility of 70%. The preferred stock warrants were converted to common stock warrants upon the completion of the IPO and are no longer subject to remeasurement.
	The following table sets forth a summary of the changes in the estimated fair value of the Company’s convertible preferred stock warrants, which were measured at fair value on a recurring basis until their conversion to common stock warrants and related reclassification to additional paid-in capital (in thousands):
		Six Months Ended June 30,
		2014			2013
	Fair value, beginning of period	$	3,419		$	518
	Change in fair value recorded as a loss in other expense, net		3,324			372
	Reclassification of warrant liability to additional paid-in capital		(6,743	)		—
	Fair value, end of period	$	—		$	890

Balance_Sheet_Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2014
Balance Sheet Components	'
	4	Balance Sheet Components
	Cash Equivalents and Short-term Investments
	The fair values of cash equivalents and short-term investments classified as available-for-sale securities, consisted of the following:
		30-Jun-14
				Gross Unrealized
		Amortized		Gains		Losses			Estimated
		Cost							Fair Value
	Money market funds classified as cash equivalents	$	6,753	$	—	$	—		$	6,753
	Corporate bonds classified as cash equivalents		1,011		—		—			1,011
	Commercial Paper classified as short-term investments		7,988		—		—			7,988
	Corporate bonds classified as short-term investments		124,883		20		(74	)		124,829
	U.S Government securities classified as short-term investments		2,996		6		—			3,002
	Total	$	143,631	$	26	$	(74	)	$	143,583
		December 31, 2013
				Gross Unrealized
		Amortized		Gains		Losses			Estimated
		Cost							Fair Value
	Money market funds classified as cash equivalents	$	6,847	$	—	$	—		$	6,847
	Commercial Paper classified as short-term investments		1,000		—		—			1,000
	Corporate bonds classified as short-term investments		44,939		17		(6	)		44,950
	Total	$	52,786	$	17	$	(6	)	$	52,797
	At June 30, 2014, the remaining contractual maturities of available-for-sale securities were less than two years. There have been no significant realized gains or losses on available-for-sale securities for the periods presented.
	Accrued Liabilities
	Accrued liabilities consist of the following (in thousands):
		June 30,		December 31,
		2014		2013
	Research and clinical study expenses	$	2,852	$	1,886
	Payroll and related expenses		2,208		2,360
	Other		218		160
	Total accrued liabilities	$	5,278	$	4,406

License_and_Research_Agreement

License and Research Agreements	6 Months Ended
	Jun. 30, 2014
License and Research Agreements	'
	5	License and Research Agreements
	Nobelpharma License Agreement
	In September 2010, the Company entered into a collaboration and license agreement with Nobelpharma Co., Ltd. (Nobelpharma). Under the terms of this collaboration and license agreement, each party granted the other party a worldwide exclusive license under certain of that party’s intellectual property related to the compound identified as N-acetylneuraminic acid, also known as sialic acid, to develop, manufacture, and commercialize products. Nobelpharma’s licensed territory includes Japan and certain other Asian countries, and the Company’s licensed territory includes the rest of the world.
	Under the collaboration and license agreement, the Company paid Nobelpharma $110,500 (10 million Yen) for the license, which was recorded as research and development expense in 2010, and also issued 76,567 shares of common stock to Nobelpharma with a minimal value. The Company is required to pay Nobelpharma royalties based on net sales upon product sales commencement. In addition, the Company is required to make certain payments to Nobelpharma based upon achievement of certain development and approval milestones. The Company paid $495,000 in development milestone payments since the inception of the agreement through June 30, 2014. The remaining total aggregate payments, if all milestones are achieved by Nobelpharma, would be 200 million Yen (approximately $2.0 million based on the exchange rate at June 30, 2014). The Company will pay a high single digit royalty on net sales in the Company’s territory and will receive a mid-single digit royalty on net sales in the Nobelpharma territory, excluding Japan, if such product sales are ever achieved. Net sales, as defined in the collaboration and license agreement, represent the net sales of products whereby the licensed compound is the active ingredient. If the products include other active ingredients, the portion of the net sales allocated to the licensed compound would be used in determining the royalty payments.
	Saint Louis University License Agreement
	In November 2010, the Company entered into a license agreement with Saint Louis University (SLU). Under the terms of this license agreement, SLU granted the Company an exclusive worldwide license to make, have made, use, import, offer for sale, and sell therapeutics related to SLU’s beta-glucuronidase product for use in the treatment of human diseases.
	Under the license agreement, the Company paid SLU an up-front fee of $10,000, which was recorded as research and development expense in 2010. The Company will be required to make a milestone payment of $100,000 upon approval of a glucuronidase-based enzyme therapy for treatment of MPS 7. Additionally, upon reaching a certain level of cumulative worldwide sales of the product, the Company will be required to pay to SLU a low single-digit royalty on net sales of the licensed products in any country or region, if such product sales are ever achieved.
	AAI Pharma License Agreement
	In March 2011, the Company entered into a license agreement with AAI Pharma Services Corp. (AAI Pharma). Under the terms of this license agreement, AAI Pharma granted the Company a fully paid-up, royalty-free, exclusive, perpetual, and irrevocable license to research, develop, make, have made, use, import, offer for sale, and sell products incorporating AAI Pharma’s controlled release matrix solid dose oral tablet. Under the license agreement, the Company will pay a mid-single digit percentage of any sublicense revenue received by Ultragenyx related to the sublicense of AAI Pharma technology that had been initially licensed by Ultragenyx.
	HIBM Research Group License Agreement
	In April 2012, the Company entered into an exclusive license agreement with HIBM Research Group (HRG). Under the terms of this license agreement, HRG granted the Company an exclusive worldwide license to certain intellectual property related to the treatment of HIBM. Under the license agreement, the Company paid HRG an up-front fee of $25,000 which was recorded as research and development expense during the year ended December 31, 2012. The Company may make future payments that aggregate up to $300,000 and that are contingent upon attainment of various development and approval milestones. Additionally, the Company will pay to HRG a royalty of less than 1% of net sales of the licensed products in the licensed territories, if such product sales are ever achieved.
	St. Jude Children’s Research Hospital License Agreement
	In September 2012, the Company entered into a license agreement with St. Jude Children’s Research Hospital (St. Jude). Under the terms of this license agreement, St. Jude granted the Company an exclusive license under certain know-how to research, develop, make, use, offer to sell, import, and otherwise commercialize and exploit St. Jude’s protective protein, cathepsin, a protein product to treat, prevent, and/or diagnose galactosialidosis and other monogenetic diseases.
	Under the license agreement, the Company paid St. Jude an up-front fee of $10,000 which was recorded as research and development expense during the year ended December 31, 2012. Additionally, the Company will pay to St. Jude a royalty of less than 1% on net sales of the licensed products in the licensed territories, if such product sales are ever achieved.
	Baylor Research Institute License Agreement
	In September 2012, the Company entered into a license agreement with Baylor Research Institute (BRI). Under the terms of this license agreement, BRI exclusively licensed to the Company certain intellectual property related to triheptanoin for North America. Under the license agreement, the Company paid BRI an up-front fee of $250,000 which was recorded as research and development expense during the year ended December 31, 2012. In June 2013, the Company notified BRI that it was exercising its option pursuant to the agreement to license the rights to triheptanoin in all territories outside of the United States, Canada and Mexico and paid the option exercise fee of $750,000.
	The Company may make future payments of up to $10.5 million contingent upon attainment of various development milestones and $7.5 million contingent upon attainment of various sales milestones. Additionally, the Company will pay to BRI a mid-single digit royalty on net sales of the licensed product in the licensed territories, if such product sales are ever achieved.
	Kyowa Hakko Kirin Collaboration and License Agreement
	In August 2013, the Company entered into a collaboration and license agreement with Kyowa Hakko Kirin Co., Ltd. (KHK). Under the terms of this collaboration and license agreement, the Company and KHK will collaborate on the development and commercialization of certain products containing KRN23, an antibody directed towards FGF23, in the field of orphan diseases in the United States and Canada, or the profit share territory, and in the European Union, Switzerland, and Turkey, or the European territory, and the Company will have the right to develop and commercialize such products in the field of orphan diseases in Mexico and Central and South America, or Latin America. In the field of orphan diseases, and except for ongoing studies being conducted by KHK, the Company will be the lead party for development activities in the profit share territory and in the European territory until the applicable transition date. The Company will share the costs for development activities in the profit share territory and European territory conducted pursuant to the development plan before the applicable transition date equally with KHK. On the applicable transition date in the relevant territory, KHK will become the lead party and be responsible for these costs. However, the Company will continue to share the costs of the studies commenced prior to the applicable transition date equally with KHK. The Company has the primary responsibility for conducting certain research and development services. The Company is obligated to provide assistance in accordance with the agreed upon development plan as well as participate on various committees. If KRN23 is approved, the Company and KHK will share commercial responsibilities and profits in the profit share territory until the applicable transition date, KHK will commercialize KRN23 in the European territory and the Company will develop and commercialize KRN23 in Latin America. KHK will manufacture and supply KRN23 for clinical use globally and will manufacture and supply KRN23 for commercial use in the profit share territory and Latin America.
	The Company is accounting for the agreement as a collaboration arrangement as defined in ASC 808, Collaborative Agreements; accordingly, the Company recognized $1.3 million and $2.0 million for its share of the costs as research and development expenses for the three and six months ended June 30, 2014 respectively.

Convertible_Preferred_Stock_Wa

Convertible Preferred Stock Warrants and Common Stock Warrants	6 Months Ended
	Jun. 30, 2014
Convertible Preferred Stock Warrants and Common Stock Warrants	'
	6	Convertible Preferred Stock Warrants and Common Stock Warrants
	Upon the closing of the Company’s IPO, the Convertible Preferred Stock warrants were converted into warrants to purchase common stock.
	As of June 30, 2014, outstanding common stock warrants consisted of the following:
	Common Stock Warrants:		Number of Warrants		Date Issued	Term	Exercise Price
	Common stock			83,167	Jun-10	10 years	$	3.006
	Common stock			203,759	Feb-11	10 years		3.006
	Common stock			66,533	Jun-11	10 years		3.006
	Total common stock warrants			353,459
	As of December 31, 2013, outstanding preferred stock warrants consisted of the following:
	Convertible Preferred Stock Warrants:		Number of Warrants		Date Issued	Term	Exercise Price
	Series A			241,803	Jun-10	10 years	$	1.034
	Series A			592,417	Feb-11	10 years		1.034
	Series A			193,442	Jun-11	10 years		1.034
	Total convertible preferred stock warrants			1,027,662
	The fair value of the warrants was estimated to be $6.7 million and $3.4 million as of January 30, 2014 (pricing date of IPO) and December 31, 2013, respectively.
	The Company recorded $0 and ($374,000), to other income (expense) for three months ended June 30, 2014 and 2013 and ($3.3 million) and($372,000) for the six months ended June 30, 2014 and 2013, representing the change in fair value of the warrants for the respective period.

Convertible_Preferred_Stock

Convertible Preferred Stock	6 Months Ended
	Jun. 30, 2014
Convertible Preferred Stock	'
	7	Convertible Preferred Stock
	The holders of the Series A and Series B convertible preferred stock were entitled to receive cumulative dividends at the rate of $0.062 per share per annum, payable in the form of cash. Dividends accrued from day to day, whether or not declared, but were paid only when, as, and if declared by the Board of Directors. During 2012, $2.1 million of dividends were declared and paid to holders of Series A convertible preferred stock in the form of additional Series A convertible preferred stock. Dividends in arrears as of December 31, 2013 were $4.0 million for both series of preferred stock. Upon the closing of the IPO in February 2014, all shares of convertible preferred stock then outstanding automatically converted in 19,598,486 shares of common stock. In connection with the conversion of the convertible preferred stock, all accrued and outstanding dividends in the amount of $4.3 million were paid.
	The Company initially recorded the Series A and Series B convertible preferred stock at their issuance price, which represents the carrying value. The Series A convertible preferred stock was redeemable at any time after June 16, 2017 once a written request to redeem such stock was received by the Company from holders of not less than seventy-five percent of the then outstanding Series A convertible preferred stock. As only the passage of time was required for the Series A convertible preferred stock to become redeemable, the difference in the initial carrying value of the Series A convertible preferred stock and their total redemption value was being accreted from the issuance date through the first redemption date of June 16, 2017. The Company recorded accretion of $0 and $1.8 million for the three months ended June 30, 2014 and 2013, respectively and $4.4 million and $2.9 million for the six months ended June 30, 2014 and 2013, respectively. As a result of the conversion of the preferred stock to common stock in connection with the Company’s IPO, the Company is no longer accreting the Series A convertible preferred stock to its previously calculated redemption value.

StockBased_Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2014
Stock-Based Compensation	'
	8	Stock-Based Compensation
	2011 Equity Incentive Plan
	In 2011, the Company adopted the 2011 Equity Incentive Plan (the 2011 Plan). The 2011 Plan provides for the granting of stock-based awards to employees, directors, and consultants under terms and provisions established by the Board of Directors. Under the terms of the 2011 Plan, options may be granted at an exercise price not less than fair market value. For employees holding more than 10% of the voting rights of all classes of stock, the exercise prices for incentive stock options must be at least 110% of fair market of the common stock on the grant date, as determined by the Board of Directors. The terms of options granted under the 2011 Plan may not exceed ten years. Options granted generally vest over a period of four years. Typically, the vesting schedule for option grants to newly hired employees provides that 1/4 of the grant vests upon the first anniversary of the employee’s date of hire, with the remainder of the shares vesting monthly thereafter at a rate of 1/48 of the total shares subject to the option. All other employee options typically vest in equal monthly installments over the four-year vesting schedule. In connection with the Company’s IPO, no further grants will be made under this plan and all remaining shares available for grant were transferred to the 2014 Incentive Plan.
	2014 Incentive Plan
	In 2014, the Company adopted the 2014 Incentive Plan (the 2014 Plan), which became effective upon the closing of the Company’s IPO in February 2014. The 2014 Plan had 2,250,000 shares of common stock available for future issuance at the time of its inception, which included 655,038 shares available under the 2011 Plan, which were transferred to the 2014 Plan upon adoption. The 2014 Plan provides for automatic annual increases in shares available for grant, beginning on January 1, 2015 through January 1, 2024. The 2014 Plan provides for the granting of stock-based awards to employees, directors, and consultants under similar terms, conditions and provisions as the 2011 Plan.
	Founder’s Stock
	In connection with the Series A preferred stock financing, the Company entered into a stock repurchase agreement with the founder on June 16, 2011, whereby 2,552,241 shares of common stock previously owned by the founder were subject to repurchase by the Company at the original issuance price in the event that the founder’s employment is terminated either voluntarily or involuntarily. The repurchase rights lapsed over a period of two years from June 16, 2011. The Company calculated the estimated fair value of these restricted shares at the time the restriction was added to the shares as $1,199,000 and recorded this amount as stock-based compensation ratably over the period that the repurchase rights lapsed. Stock-based compensation expense pertaining to the founder’s stock was $0, and $119,000 for the three months ended June 30, 2014 and 2013, respectively and $0 and $268,000 for the six months ended June 30, 2014 and 2013, respectively.
	The table below sets forth the functional classification of stock-based compensation expense, net of estimated forfeitures, for the periods presented (in thousands):
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Research and development	$	652	$	52	$	1,357	$	82
	General and administrative		294		133		384		294
	Total stock-based compensation	$	946	$	185	$	1,741	$	376

Defined_Contribution_Plan

Defined Contribution Plan	6 Months Ended
	Jun. 30, 2014
Defined Contribution Plan	'
	9	Defined Contribution Plan
	In March 2013, the Company began to sponsor a 401(k) retirement plan, in which substantially all of its full-time employees are eligible to participate. Eligible participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. The Company has not provided any contributions to the plan since its inception through June 30, 2014.

Commitment_and_Contingencies

Commitment and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies	'
	10	Commitments and Contingencies
	Commitments
	The Company has various manufacturing, clinical, research, and other contracts with vendors in the conduct of the normal course of its business. As of June 30, 2014, the Company had a binding obligation for approximately $780,000 with a manufacturing vendor for the production of a drug substance for one of its product candidates.  All other significant contracts as of June 30, 2014 were terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, the Company would only be obligated for the products or services that the Company had received at the time the termination became effective.
	Contingencies
	While there are no legal proceedings the Company is aware of, the Company may become party to various claims and complaints arising in the ordinary course of business. Management does not believe that any ultimate liability resulting from any such claims will have a material adverse effect on its results of operations, financial position, or liquidity. However, management cannot give any assurance regarding the ultimate outcome of such claims, and their resolution could be material to the Company for any particular period, depending upon the level of income or loss for the period, as well as the Company’s balance sheet.

Net_Loss_per_Share_Attributabl

Net Loss per Share Attributable to Common Stockholders	6 Months Ended
	Jun. 30, 2014
Net Loss per Share Attributable to Common Stockholders	'
	11	Net Loss per Share Attributable to Common Stockholders
	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data):
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Numerator:
	Net loss	$	(13,585	)	$	(8,590	)	$	(27,215	)	$	(15,325	)
	Accretion and dividends on convertible preferred stock		-			(2,239	)		(4,808	)		(3,709	)
	Net loss attributable to common stockholders	$	(13,585	)	$	(10,829	)	$	(32,023	)	$	(19,034	)
	Denominator:
	Weighted-average common shares outstanding		30,055,943			3,503,214			25,697,407			3,482,304
	Less: weighted-average unvested common shares subject to repurchase		—			(245,408	)		—			(405,397	)
	Weighted-average shares used to compute net loss per share attributable		30,055,943			3,257,806			25,697,407			3,076,907
	to common stockholders, basic and diluted
	Net loss per share attributable to common stockholders, basic and diluted	$	(0.45	)	$	(3.32	)	$	(1.25	)	$	(6.19	)
	The following weighted-average outstanding common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Convertible preferred stock		—			19,598,486			3,248,368			19,598,486
	Stock options to purchase common stock		2,561,357			1,647,753			2,438,351			1,543,954
	Common stock subject to repurchase		—			245,408			—			405,397
	Warrants to purchase convertible preferred stock		—			353,459			294,875			353,459
	(as if converted)
	Warrants to purchase common stock		353,459			—			58,584			—
			2,914,816			21,845,106			6,040,178			21,901,296

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events	'
	12	Subsequent Events
	In July 2014, we completed an underwritten public offering in which we sold 1,613,879 shares of our common stock, which included 302,602 shares purchased by the underwriters pursuant to an option granted to them in connection with the offering, at a public offering price of $40.00 per share. In addition, certain existing stockholders sold 706,072 shares of common stock in the underwritten public offering at the same per-share price. The total proceeds the Company received from the offering were approximately $60.7 million, net of underwriting discounts and commissions of approximately $3.9 million. After deducting estimated offering expenses payable by us of approximately $0.4 million, net proceeds to us were $60.2 million.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. general accepted accounting principles (“U.S. GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. The unaudited interim consolidated financial statements have been prepared on the same basis as the annual financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation. These financial statements should be read in conjunction with the audited financial statements and notes thereto for the preceding fiscal year contained in the Company’s Annual Report on Form 10-K filed on March 24, 2014 with the SEC.
	The results of operations for the three and six months ended June 30, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014. The condensed balance sheet as of December 31, 2013 has been derived from audited financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements.
Reverse Stock Split	'
	Reverse Stock Split
	In January 2014, the Company’s board of directors and its stockholders approved an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock on a 1-for-3.1345 basis (the “Reverse Stock Split”). The par values and the authorized shares of the common and convertible preferred stock were not adjusted as a result of the Reverse Stock Split, nor were the outstanding shares of preferred stock. All issued and outstanding common stock and related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. A proportional adjustment to the conversion ratio for each series of convertible preferred stock was also effected in connection with the Reverse Stock Split. The Reverse Stock Split was effected on January 17, 2014.
Use of Estimates	'
	Use of Estimates
	The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical study accruals, fair value of assets and liabilities, convertible preferred stock and related warrants, common stock, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts.
Short-Term Investments	'
	Short-Term Investments
	All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and were reported as a component of comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest income and other expense, respectively. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest income.
Deferred Offering Costs	'
	Deferred Offering Costs
	Deferred offering costs, which primarily consist of direct incremental accounting, legal and printing fees relating to the IPO and to the Company’s underwritten public offering in July 2014, were initially capitalized. IPO deferred offering costs of $3.3 million were subsequently offset against IPO proceeds upon the completion of the IPO in February 2014. Underwritten public offering costs of $444,000 were subsequently offset against offering proceeds on completion of our underwritten public offering in July 2014. As of June 30, 2014 and December 31, 2013, deferred offering costs of $316,000 and $2.3 million, respectively, were capitalized and included in prepaid and other current assets on the balance sheet.
Concentration of Credit Risk and Other Risks and Uncertainties	'
	Concentration of Credit Risk and Other Risks and Uncertainties
	Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents, and marketable securities. The Company’s cash, cash equivalents, and short-term investments are held by financial institutions that management believes are of high credit quality. The Company’s investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as U.S. government obligations, money market instruments and funds, corporate bonds, and asset-backed securities and places restrictions on maturities and concentrations by type and issuer. Such deposits may, at times, exceed federally insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents and its accounts are monitored by management to mitigate risk. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and corporate bond issuers to the extent recorded in the balance sheets.
Income Taxes	'
	Income Taxes
	The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.
	The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.
Net Loss per Share Attributable to Common Stockholders	'
	Net Loss per Share Attributable to Common Stockholders
	Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. The net loss attributable to common stockholders is calculated by adjusting the net loss of the Company for the accretion on the Series A convertible preferred stock and cumulative dividends paid on Series A and B convertible preferred stock. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since the effects of potentially dilutive securities are antidilutive.
Recently Issued Accounting Pronouncements	'
	Recently Issued Accounting Pronouncements
	In June 2014, the Financial Accounting Standards Board issued Accounting Standards Update 2014-10, Development Stage Enterprises: Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation (ASU 2014-10). ASU 2014-10 removes the definition of a development stage entity from the Master Glossary of the Accounting Standards Codification, thereby removing the financial reporting distinction between development stage entities and other reporting entities from U.S. GAAP. ASU 2014-10 also eliminates the requirements for development stage entities to (1) present inception-to-date information in the statements of income, cash flows, and shareholder equity, (2) label the financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged, and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. The amendments also clarify that the guidance in Topic 275, Risks and Uncertainties, is applicable to entities that have not commenced planned principal operations. The amendments in ASU 2014-10 will be effective retrospectively except for the clarification to Topic 275, which shall be applied prospectively for annual reporting periods beginning after December 15, 2014, and interim periods therein. Early application of each of the amendments is permitted for any annual reporting period or interim period for which the entity’s financial statements have not yet been issued. The Company elected to early adopt the provisions of ASU 2014-10 in the second quarter of 2014, as reflected in this Quarterly Report.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
Summary of Financial Assets and Liabilities Measured on Recurring Basis	'
	The following tables set forth the fair value of the Company’s financial assets and liabilities remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands):
		30-Jun-14
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	6,753		$	—	$	—	$	6,753
	Commercial paper		—			7,988		—		7,988
	Corporate bonds		—			125,840		—		125,840
	U.S. Government securities		—			3,002		—		3,002
	Total financial assets	$	6,753		$	136,830	$	—	$	143,583
		December 31, 2013
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	6,847		$	—	$	—	$	6,847
	Commercial paper		—			1,000		—		1,000
	Corporate bonds		—			44,950		—		44,950
	Total financial assets	$	6,847		$	45,950	$	—	$	52,797
	Financial Liabilities:
	Convertible preferred stock warrant liability	$	—		$	—	$	3,419	$	3,419
	Total financial liabilities	$	—		$	—	$	3,419	$	3,419
Summary of Changes in Estimated Fair Value	'
	The following table sets forth a summary of the changes in the estimated fair value of the Company’s convertible preferred stock warrants, which were measured at fair value on a recurring basis until their conversion to common stock warrants and related reclassification to additional paid-in capital (in thousands):
		Six Months Ended June 30,
		2014			2013
	Fair value, beginning of period	$	3,419		$	518
	Change in fair value recorded as a loss in other expense, net		3,324			372
	Reclassification of warrant liability to additional paid-in capital		(6,743	)		—
	Fair value, end of period	$	—		$	890

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2014
Summary of Fair Values of Cash Equivalents and Short-Term Investments Classified as Available-for-Sale Securities	'
	The fair values of cash equivalents and short-term investments classified as available-for-sale securities, consisted of the following:
		30-Jun-14
				Gross Unrealized
		Amortized		Gains		Losses			Estimated
		Cost							Fair Value
	Money market funds classified as cash equivalents	$	6,753	$	—	$	—		$	6,753
	Corporate bonds classified as cash equivalents		1,011		—		—			1,011
	Commercial Paper classified as short-term investments		7,988		—		—			7,988
	Corporate bonds classified as short-term investments		124,883		20		(74	)		124,829
	U.S Government securities classified as short-term investments		2,996		6		—			3,002
	Total	$	143,631	$	26	$	(74	)	$	143,583
		December 31, 2013
				Gross Unrealized
		Amortized		Gains		Losses			Estimated
		Cost							Fair Value
	Money market funds classified as cash equivalents	$	6,847	$	—	$	—		$	6,847
	Commercial Paper classified as short-term investments		1,000		—		—			1,000
	Corporate bonds classified as short-term investments		44,939		17		(6	)		44,950
	Total	$	52,786	$	17	$	(6	)	$	52,797
Accrued Liabilities	'
	Accrued liabilities consist of the following (in thousands):
		June 30,		December 31,
		2014		2013
	Research and clinical study expenses	$	2,852	$	1,886
	Payroll and related expenses		2,208		2,360
	Other		218		160
	Total accrued liabilities	$	5,278	$	4,406

Convertible_Preferred_Stock_Wa1

Convertible Preferred Stock Warrants and Common Stock Warrants (Tables)	6 Months Ended
	Jun. 30, 2014
Common Stock Warrants	'
Summary of Outstanding Warrants	'
	As of June 30, 2014, outstanding common stock warrants consisted of the following:
	Common Stock Warrants:	Number of Warrants		Date Issued	Term	Exercise Price
	Common stock		83,167	Jun-10	10 years	$	3.006
	Common stock		203,759	Feb-11	10 years		3.006
	Common stock		66,533	Jun-11	10 years		3.006
	Total common stock warrants		353,459
Convertible Preferred Stock Warrants	'
Summary of Outstanding Warrants	'
	As of December 31, 2013, outstanding preferred stock warrants consisted of the following:
	Convertible Preferred Stock Warrants:	Number of Warrants		Date Issued	Term	Exercise Price
	Series A		241,803	Jun-10	10 years	$	1.034
	Series A		592,417	Feb-11	10 years		1.034
	Series A		193,442	Jun-11	10 years		1.034
	Total convertible preferred stock warrants		1,027,662

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2014
Functional Classification of Stock-Based Compensation Expense, Net of Estimated Forfeitures	'
	The table below sets forth the functional classification of stock-based compensation expense, net of estimated forfeitures, for the periods presented (in thousands):
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Research and development	$	652	$	52	$	1,357	$	82
	General and administrative		294		133		384		294
	Total stock-based compensation	$	946	$	185	$	1,741	$	376

Net_Loss_per_Share_Attributabl1

Net Loss per Share Attributable to Common Stockholders (Tables)	6 Months Ended
	Jun. 30, 2014
Computation of Basic and Diluted Net Loss per Share	'
	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data):
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Numerator:
	Net loss	$	(13,585	)	$	(8,590	)	$	(27,215	)	$	(15,325	)
	Accretion and dividends on convertible preferred stock		-			(2,239	)		(4,808	)		(3,709	)
	Net loss attributable to common stockholders	$	(13,585	)	$	(10,829	)	$	(32,023	)	$	(19,034	)
	Denominator:
	Weighted-average common shares outstanding		30,055,943			3,503,214			25,697,407			3,482,304
	Less: weighted-average unvested common shares subject to repurchase		—			(245,408	)		—			(405,397	)
	Weighted-average shares used to compute net loss per share attributable		30,055,943			3,257,806			25,697,407			3,076,907
	to common stockholders, basic and diluted
	Net loss per share attributable to common stockholders, basic and diluted	$	(0.45	)	$	(3.32	)	$	(1.25	)	$	(6.19	)
Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share	'
	The following weighted-average outstanding common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Convertible preferred stock		—			19,598,486			3,248,368			19,598,486
	Stock options to purchase common stock		2,561,357			1,647,753			2,438,351			1,543,954
	Common stock subject to repurchase		—			245,408			—			405,397
	Warrants to purchase convertible preferred stock		—			353,459			294,875			353,459
	(as if converted)
	Warrants to purchase common stock		353,459			—			58,584			—
			2,914,816			21,845,106			6,040,178			21,901,296

Organization_Additional_Inform

Organization - Additional Information (Details) (USD $)	6 Months Ended			0 Months Ended	6 Months Ended		0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Feb. 05, 2014	Jun. 30, 2014	Jan. 30, 2014	Feb. 05, 2014
				IPO	IPO	IPO	IPO
							Underwriters Overallotment Option
Organization And Nature Of Business [Line Items]	'	'	'	'	'	'	'
Effective date of registration	'	'	'	'	30-Jan-14	'	'
Public offering price of the shares sold	'	'	'	'	'	$21	'
Common stock issued in initial public offering	'	'	'	6,624,423	'	'	864,054
Net proceeds from issuance of common stock	$126,110,000	$57,000	'	$129,400,000	'	'	'
Underwriting discounts and commissions	'	'	'	9,700,000	'	'	'
Offering expenses	'	'	'	3,300,000	'	'	'
Cash dividends paid to preferred stockholders	'	'	'	4,300,000	'	'	'
Net proceeds from initial public offering	'	'	'	$121,700,000	'	'	'
Number of preferred stock converted into common stock	'	'	'	19,598,486	'	'	'
Authorized capital stock including preferred shares	275,000,000	'	'	'	'	'	'
Common stock, shares authorized	250,000,000	'	250,000,000	'	'	'	'
Preferred stock, shares authorized	25,000,000	'	25,000,000	'	'	'	'
Preferred stock, par value	$0.00	'	$0.00	'	'	'	'
Common stock, par value	$0.00	'	$0.00	'	'	'	'
Preferred stock, shares outstanding	0	'	0	'	'	'	'

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Details) (USD $)	1 Months Ended
	Jan. 17, 2014	Jun. 30, 2014	Mar. 31, 2014	Feb. 05, 2014	Jun. 30, 2014	Dec. 31, 2013
		Underwritten Offering Costs	IPO	IPO	Prepaid and Other Current Assets	Prepaid and Other Current Assets
					Costs Capitalized	Costs Capitalized
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'	'	'
Reverse stock split ratio on preferred and common stock	0.319	'	'	'	'	'
Deferred offering Costs	'	'	$3,300,000	'	$316,000	$2,300,000
Offering expenses	'	$444,000	'	$3,300,000	'	'

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured on Recurring Basis (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Assets:	'	'
Fair value	$143,583	$52,797
Financial Liabilities:	'	'
Fair value	'	3,419
Money Market Funds	'	'
Financial Assets:	'	'
Fair value	6,753	6,847
Commercial Paper	'	'
Financial Assets:	'	'
Fair value	7,988	1,000
U.S. Government Securities	'	'
Financial Assets:	'	'
Fair value	3,002	'
Level 1	'	'
Financial Assets:	'	'
Fair value	6,753	6,847
Level 1 | Money Market Funds	'	'
Financial Assets:	'	'
Fair value	6,753	6,847
Level 2	'	'
Financial Assets:	'	'
Fair value	136,830	45,950
Level 2 | Commercial Paper	'	'
Financial Assets:	'	'
Fair value	7,988	1,000
Level 2 | U.S. Government Securities	'	'
Financial Assets:	'	'
Fair value	3,002	'
Level 3	'	'
Financial Liabilities:	'	'
Fair value	'	3,419
Corporate Bonds	'	'
Financial Assets:	'	'
Fair value	125,840	44,950
Corporate Bonds | Level 2	'	'
Financial Assets:	'	'
Fair value	125,840	44,950
Convertible Preferred Stock Warrant Liability	'	'
Financial Liabilities:	'	'
Fair value	'	3,419
Convertible Preferred Stock Warrant Liability | Level 3	'	'
Financial Liabilities:	'	'
Fair value	'	$3,419

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Details) (USD $)	1 Months Ended
	Dec. 31, 2013	Jan. 30, 2014
	Back Solve Method	Black-Scholes Option Pricing Model
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]	'	'
Estimated fair value of common stock, per share	$12.14	$21
Expected volatility	70.00%	70.00%
Expected time	'5 months 5 days	'7 years
Expected risk free interest rate	0.11%	2.19%

Fair_Value_Measurements_Summar1

Fair Value Measurements - Summary of Changes in Estimated Fair Value (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Fair Value Inputs Assets Quantitative Information [Line Items]	'	'
Fair value, beginning of period	$3,419	$518
Change in fair value recorded as a loss in other expense, net	3,324	372
Reclassification of warrant liability to additional paid-in capital	-6,743	'
Fair value, end of period	'	$890

Balance_Sheet_Components_Summa

Balance Sheet Components - Summary of Fair Values of Cash Equivalents and Short-Term Investments Classified as Available-for-Sale Securities (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	$143,631	$52,786
Gross Unrealized Gains	26	17
Gross Unrealized Losses	-74	-6
Estimated Fair Value	143,583	52,797
Money Market Funds	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	6,753	6,847
Estimated Fair Value	6,753	6,847
Corporate bonds classified as cash equivalents	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	1,011	'
Estimated Fair Value	1,011	'
Commercial Paper classified as short-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	7,988	1,000
Estimated Fair Value	7,988	1,000
Corporate bonds classified as short-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	124,883	44,939
Gross Unrealized Gains	20	17
Gross Unrealized Losses	-74	-6
Estimated Fair Value	124,829	44,950
U.S Government securities classified as short-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Amortized Cost	2,996	'
Gross Unrealized Gains	6	'
Estimated Fair Value	$3,002	'

Balance_Sheet_Components_Addit

Balance Sheet Components - Additional Information (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Schedule Of Available For Sale Securities [Line Items]	'
Available-for-sale Securities, Gross Realized Gain (Loss)	$0
Maximum	'
Schedule Of Available For Sale Securities [Line Items]	'
Available-for-sale securities remaining contractual maturities	'2 years

Balance_Sheet_Components_Accru

Balance Sheet Components - Accrued Liabilities (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Liabilities [Line Items]	'	'
Research and clinical study expenses	$2,852	$1,886
Payroll and related expenses	2,208	2,360
Other	218	160
Total accrued liabilities	$5,278	$4,406

License_and_Research_Agreement1

License and Research Agreements - Additional Information (Details)

Jun. 30, 2014

Dec. 31, 2013

Sep. 30, 2010

Sep. 30, 2010

Jun. 30, 2014

Jun. 30, 2014

Nov. 30, 2010

Jun. 30, 2014

Dec. 31, 2012

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2012

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2012

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Nobelpharma License Agreement

Nobelpharma License Agreement

Nobelpharma License Agreement

Nobelpharma License Agreement

Saint Louis University License Agreement

Saint Louis University License Agreement

H I B M Research Group

H I B M Research Group

H I B M Research Group

St. Jude Children's Research Hospital License Agreement

St. Jude Children's Research Hospital License Agreement

Baylor Research Institute License Agreement

Baylor Research Institute License Agreement

Baylor Research Institute License Agreement

Baylor Research Institute License Agreement

Kyowa Hakko Kirin Collaboration

Kyowa Hakko Kirin Collaboration

USD ($)

JPY (¥)

USD ($)

JPY (¥)

USD ($)

USD ($)

USD ($)

Maximum

Development and Approval Milestones

USD ($)

Maximum

USD ($)

USD ($)

Development Milestones

Sales Milestones

License Agreement

License Agreement

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Research And Development [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

License agreement

'

'

$110,500

¥ 10,000,000

'

'

$10,000

'

$25,000

'

'

$10,000

'

'

$250,000

'

'

$1,300,000

$2,000,000

Common stock, shares issued

30,059,288

3,766,289

76,567

76,567

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments of milestone

'

'

'

'

495,000

'

'

100,000

'

'

'

'

'

'

'

'

'

'

'

Remaining total aggregate payments

'

'

'

'

2,000,000

200,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Future contingent milestone payments

'

'

'

'

'

'

'

'

'

'

300,000

'

'

'

'

10,500,000

7,500,000

'

'

Payments for royalty on net sales

'

'

'

'

'

'

'

'

'

1.00%

'

'

1.00%

'

'

'

'

'

'

Payment of option exercise fee

'

'

'

'

'

'

'

'

'

'

'

'

'

$750,000

'

'

'

'

'

Convertible_Preferred_Stock_Wa2

Convertible Preferred Stock Warrants and Common Stock Warrants - Summary of Outstanding Warrants (Details)	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
	Common Stock	Common Stock	Common Stock	Common Stock	Convertible Preferred Stock	Convertible Preferred Stock	Convertible Preferred Stock	Convertible Preferred Stock
		June 2010 Common Stock Warrants	February 2011 Common Stock Warrants	June 2011 Common Stock Warrants		June 2010 Series A Convertible Preferred Stock Warrant	February 2011 Series A Convertible Preferred Stock Warrant	June 2011 Series A Convertible Preferred Stock Warrants
Class Of Warrant Or Right [Line Items]	'	'	'	'	'	'	'	'
Number of Warrants	353,459	83,167	203,759	66,533	1,027,662	241,803	592,417	193,442
Date Issued	'	'2010-06	'2011-02	'2011-06	'	'2010-06	'2011-02	'2011-06
Term	'	'10 years	'10 years	'10 years	'	'10 years	'10 years	'10 years
Exercise Price	'	3.006	3.006	3.006	'	1.034	1.034	1.034

Convertible_Preferred_Stock_Wa3

Convertible Preferred Stock Warrants and Common Stock Warrants - Additional Information (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jan. 30, 2014
						Warrant	Warrant	Warrant	Warrant	IPO
Class Of Warrant Or Right [Line Items]	'	'	'	'	'	'	'	'	'	'
Fair value of the warrants	'	'	'	'	$3,400,000	'	'	'	'	$6,700,000
Other income (expense)	$76,000	($343,000)	($3,215,000)	($331,000)	'	$0	($374,000)	($3,300,000)	($372,000)	'

Convertible_Preferred_Stock_Ad

Convertible Preferred Stock - Additional Information (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Feb. 05, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2014	Dec. 31, 2013
		Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series B Convertible Preferred Stock
Convertible Preferred Stock [Line Items]	'	'	'	'	'	'	'	'	'
Dividends per share	'	'	'	$0.06	'	'	'	$0.06	'
Amount of dividends declared and paid	'	'	'	'	'	'	$2.10	'	'
Amount of dividends in arrears paid	'	'	'	'	'	4	'	'	4
Conversion of preferred stock into common stock, shares	19,598,486	'	'	'	'	'	'	'	'
Amount of dividends accrued and outstanding paid	4.3	'	'	'	'	'	'	'	'
Convertible preferred stock redemption terms	'	'	'	'The Series A convertible preferred stock was redeemable at any time after June 16, 2017 once a written request to redeem such stock was received by the Company from holders of not less than seventy-five percent of the then outstanding Series A convertible preferred stock.	'	'	'	'	'
Convertible preferred stock redemption date	'	'	'	16-Jun-17	'	'	'	'	'
Accretion of preferred stock redemption	'	$0	$1.80	$4.40	$2.90	'	'	'	'

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Details) (USD $)

6 Months Ended

3 Months Ended

6 Months Ended

6 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 16, 2011

Jun. 30, 2014

Feb. 05, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Feb. 05, 2014

Founder's Stock

Founder's Stock

Founder's Stock

Founder's Stock

Founder's Stock

2011 Equity Incentive Plan

2011 Equity Incentive Plan

2011 Equity Incentive Plan

2011 Equity Incentive Plan

2014 Incentive Plan

2014 Incentive Plan

First Anniversary

Maximum

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

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum percentage of voting rights of all classes of stock

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

Percentage of statutory stock options

'

'

'

'

'

'

'

110.00%

'

'

'

'

'

Options expiration period

'

'

'

'

'

'

'

'

'

'

'10 years

'

'

Options vesting period

'

'

'

'

'

'

'

'4 years

'

'

'

'

'

Option vesting rights, percentage

'

'

'

'

'

'

'

2.08%

'

25.00%

'

'

'

Share of common stock available for future issuance

'

'

'

'

'

'

'

'

655,038

'

'

'

2,250,000

Automatic increases in shares available for grant effective date

'

'

'

'

'

'

'

'

'

'

'

1-Jan-15

'

Shares available for grant, ending date

'

'

'

'

'

'

'

'

'

'

'

1-Jan-24

'

Number of shares authorized to be repurchased

'

'

'

'

'

'

2,552,241

'

'

'

'

'

'

Repurchase rights expiration period

'

'

'

'

'2 years

'

'

'

'

'

'

'

'

Estimated fair value of restricted shares

'

'

'

'

$1,199,000

'

'

'

'

'

'

'

'

Stock-based compensation expense

$1,741,000

$376,000

$0

$119,000

$0

$268,000

'

'

'

'

'

'

'

StockBased_Compensation_Functi

Stock-Based Compensation - Functional Classification of Stock-Based Compensation Expense, Net of Estimated Forfeitures (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$946	$185	$1,741	$376
Research and development	'	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	652	52	1,357	82
General and administrative	'	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$294	$133	$384	$294

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Details) (USD $)	Jun. 30, 2014
Long Term Purchase Commitment [Line Items]	'
Purchase Obligation	$780,000

Net_Loss_per_Share_Attributabl2

Net Loss per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:	'	'	'	'
Net loss	($13,585)	($8,590)	($27,215)	($15,325)
Accretion and dividends on convertible preferred stock	'	-2,239	-4,808	-3,709
Net loss attributable to common stockholders	($13,585)	($10,829)	($32,023)	($19,034)
Denominator:	'	'	'	'
Weighted-average common shares outstanding	30,055,943	3,503,214	25,697,407	3,482,304
Less: weighted-average unvested common shares subject to repurchase	'	-245,408	'	-405,397
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	30,055,943	3,257,806	25,697,407	3,076,907
Net loss per share attributable to common stockholders, basic and diluted	($0.45)	($3.32)	($1.25)	($6.19)

Net_Loss_per_Share_Attributabl3

Net Loss per Share Attributable to Common Stockholders - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	2,914,816	21,845,106	6,040,178	21,901,296
Convertible Preferred Stock	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	'	19,598,486	3,248,368	19,598,486
Stock Options to Purchase Common Stock	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	2,561,357	1,647,753	2,438,351	1,543,954
Common Stock Subject to Repurchase	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	'	245,408	'	405,397
Warrants to Purchase Convertible Preferred Stock (as if converted)	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	'	353,459	294,875	353,459
Warrants to Purchase Common Stock	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from computation of diluted net loss per share	353,459	'	58,584	'

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jul. 31, 2014
			Subsequent Event
Subsequent Event [Line Items]	'	'	'
Common stock, shares issued	30,059,288	3,766,289	1,613,879
Common stock sold by existing shareholders	'	'	706,072
Purchase of additional shares by underwriters	'	'	302,602
Common stock issued price per share	'	'	$40
Proceeds from public offering before offering expenses	'	'	$60,700,000
Underwriting discounts and commissions	'	'	3,900,000
Offering expenses	'	'	400,000
Proceeds from public offering, net	'	'	$60,200,000