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Stock Plans and Stock-Based Compensation - Employee Stock Purchase Programs (Detail) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | 90 Months Ended | ||
|---|---|---|---|---|
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2011
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Dec. 31, 2013
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|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock-based compensation expense | $ 5,902 | $ 3,638 | $ 1,469 | $ 13,414 |
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Employee Awards [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock-based compensation expense | 4,867 | 2,408 | 520 | 8,072 |
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Non-Employee Awards [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock-based compensation expense | 897 | 664 | 662 | 4,310 |
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Non-Employee Warrants [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock-based compensation expense | $ 138 | $ 566 | $ 287 | $ 1,032 |