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Common Stock - Summary of Share-Based Compensation Expense for Stock Options and Restricted Stock (Detail) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
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Sep. 30, 2014
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Sep. 30, 2013
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Sep. 30, 2014
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Sep. 30, 2013
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | $ 952 | $ 887 | $ 2,968 | $ 2,490 |
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Research and development [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | 513 | 410 | 1,454 | 1,137 |
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General and administrative [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||||
| Total stock-based compensation | $ 439 | $ 477 | $ 1,514 | $ 1,353 |