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Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Level 3 Liability (Detail) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2013
|
Dec. 31, 2012
|
|
| Fair Value Disclosures [Abstract] | ||
| Balance beginning of period | $ 161 | $ 212 |
| Additions to Level 3 | ||
| Payments | (178) | (89) |
| Change in fair value (included within research and development expense) | 17 | 38 |
| Balance end of period | $ 161 | |