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Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail) (USD $)
In Thousands, unless otherwise specified |
Mar. 31, 2014
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Dec. 31, 2013
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October 2009 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | $ 11,620 | $ 11,320 |
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March 2011 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | 10,344 | 12,101 |
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Total Common Stock Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | 21,964 | 23,421 |
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Basis of Fair Value Measurements, Level 1 [Member] | October 2009 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 1 [Member] | March 2011 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 1 [Member] | Total Common Stock Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 2 [Member] | October 2009 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 2 [Member] | March 2011 Warrants [Member]
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||
| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 2 [Member] | Total Common Stock Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | ||
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Basis of Fair Value Measurements, Level 3 [Member] | October 2009 Warrants [Member]
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| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | 11,620 | 11,320 |
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Basis of Fair Value Measurements, Level 3 [Member] | March 2011 Warrants [Member]
|
||
| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | 10,344 | 12,101 |
|
Basis of Fair Value Measurements, Level 3 [Member] | Total Common Stock Warrants [Member]
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||
| Class of Warrant or Right [Line Items] | ||
| Financial liabilities subject to fair value measurements | $ 21,964 | $ 23,421 |