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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 | |
|---|---|---|
|
Mar. 31, 2014
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Mar. 31, 2013
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Total stock-based compensation | $ 1,000 | $ 748 |
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Research and development [Member]
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Total stock-based compensation | 447 | 312 |
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General and administrative [Member]
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Total stock-based compensation | $ 553 | $ 436 |