Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail)

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Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2014
Dec. 31, 2013
October 2009 Offering [Member]
   
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Risk-free interest rate 0.13% 0.13%
Expected life (in years) 6 months 7 days 9 months 4 days
Dividend yield      
Volatility 44.00% 49.00%
Stock price $ 4.76 $ 4.67
March 2011 Offering [Member]
   
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Risk-free interest rate 0.44% 0.78%
Expected life (in years) 1 year 11 months 16 days 2 years 2 months 16 days
Dividend yield      
Volatility 55.00% 88.00%
Stock price $ 4.76 $ 4.67