|
Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2013
|
Dec. 31, 2012
|
|---|---|---|
| Assets | ||
| Total assets | $ 39,536 | $ 75,697 |
|
Stock warrants [Member]
|
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| Liabilities | ||
| Liabilities | 214 | 3,422 |
|
Cash [Member]
|
||
| Assets | ||
| Total assets | 10,575 | 2,440 |
|
Money market securities [Member]
|
||
| Assets | ||
| Total assets | 4,018 | 15,635 |
|
Restricted cash [Member]
|
||
| Assets | ||
| Total assets | 314 | 314 |
|
Corporate bonds and commercial paper [Member]
|
||
| Assets | ||
| Total assets | 24,629 | 57,308 |
|
Level 1 [Member]
|
||
| Assets | ||
| Total assets | 14,907 | 18,389 |
|
Level 1 [Member] | Stock warrants [Member]
|
||
| Liabilities | ||
| Liabilities | ||
|
Level 1 [Member] | Cash [Member]
|
||
| Assets | ||
| Total assets | 10,575 | 2,440 |
|
Level 1 [Member] | Money market securities [Member]
|
||
| Assets | ||
| Total assets | 4,018 | 15,635 |
|
Level 1 [Member] | Restricted cash [Member]
|
||
| Assets | ||
| Total assets | 314 | 314 |
|
Level 1 [Member] | Corporate bonds and commercial paper [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 2 [Member]
|
||
| Assets | ||
| Total assets | 24,629 | 57,308 |
|
Level 2 [Member] | Stock warrants [Member]
|
||
| Liabilities | ||
| Liabilities | ||
|
Level 2 [Member] | Cash [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 2 [Member] | Money market securities [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 2 [Member] | Restricted cash [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 2 [Member] | Corporate bonds and commercial paper [Member]
|
||
| Assets | ||
| Total assets | 24,629 | 57,308 |
|
Level 3 [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 3 [Member] | Stock warrants [Member]
|
||
| Liabilities | ||
| Liabilities | 214 | 3,422 |
|
Level 3 [Member] | Cash [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 3 [Member] | Money market securities [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 3 [Member] | Restricted cash [Member]
|
||
| Assets | ||
| Total assets | ||
|
Level 3 [Member] | Corporate bonds and commercial paper [Member]
|
||
| Assets | ||
| Total assets |