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Subsequent Events - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified |  |  |  |  |  | 1 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Oct. 16, 2013 Subsequent Event [Member] | Feb. 07, 2014 Subsequent Event [Member] Servier [Member] Second Right to Develop Collaboration [Member] | Oct. 31, 2013 Subsequent Event [Member] IPO [Member] | Oct. 16, 2013 Subsequent Event [Member] IPO [Member]
Subsequent Event [Line Items] |  |  |  |  |  |  |
Initial public offering number of share sold |  |  |  |  |  | 5,000,000 |
Initial public offering price per share |  |  |  |  |  |  | $ 16.00
Additional shares sold under over-allotments Option to underwriter |  |  |  |  |  | 750,000 |
Proceeds from initial public offering net of expenses |  |  |  |  |  | $ 83.8 |
Common stock, shares issued | 2,124,624 | 1,098,914 | 1,049,030 | 25,020,288 |  |  |
Common stock, shares outstanding | 2,124,624 | 1,098,914 | 1,049,030 | 25,020,288 |  |  |
Preferred stock, shares outstanding |  |  |  | 0 |  |  |
Milestone Payments Triggered | 5.0 |  |  |  |  |  |
Research Maintenance Payment | 4.0 |  |  |  |  |  |
License grant fees earned |  |  |  |  | 15 |  |
Clinical milestone payments earned |  |  |  |  | $ 5 |  |

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