Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail)

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Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail) (Warrants, USD $)
In Thousands, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
October 2009 Warrants
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements $ 8,190 $ 11,320
October 2009 Warrants | Basis of Fair Value Measurements, Level 3
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements 8,190 11,320
March 2011 Warrants
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements 7,109 12,101
March 2011 Warrants | Basis of Fair Value Measurements, Level 3
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements 7,109 12,101
Total Common Stock Warrants
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements 15,299 23,421
Total Common Stock Warrants | Basis of Fair Value Measurements, Level 3
   
Class Of Warrant Or Right [Line Items]    
Financial liabilities subject to fair value measurements $ 15,299 $ 23,421