Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Deficit) - Outstanding Warrants Valuation Assumption (Detail)

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Stockholders' Equity (Deficit) - Outstanding Warrants Valuation Assumption (Detail) (USD $)
9 Months Ended 12 Months Ended
Sep. 30, 2014
Dec. 31, 2013
October 2009 Offering
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate 0.02% 0.13%
Expected life (in years) 4 days 9 months 4 days
Dividend yield 0.00% 0.00%
Volatility 47.00% 49.00%
Stock price $ 3.61 $ 4.67
March 2011 Offering
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate 0.58% 0.78%
Expected life (in years) 1 year 5 months 16 days 2 years 2 months 16 days
Dividend yield 0.00% 0.00%
Volatility 45.00% 88.00%
Stock price $ 3.61 $ 4.67