Quarterly report pursuant to Section 13 or 15(d)

Common Stock Warrants - Additional Information (Detail)

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Common Stock Warrants - Additional Information (Detail) (USD $)
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Class of Warrant or Right [Line Items]    
Proceeds from sale of common stock $ 25,430,000 $ 23,975,000
Fair value of warrant liabilities 400,000  
Warrants, Exercise price of $5.75 per share [Member]
   
Class of Warrant or Right [Line Items]    
Issued warrants to purchase common stock 120,800  
Proceeds from sale of common stock $ 3,000,000  
Exercise price of common stock $ 5.75  
Warrant term 5 years