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) - $ / shares
6 Months Ended 12 Months Ended
Feb. 18, 2015
Jun. 30, 2015
Dec. 31, 2014
March 2011 Warrants      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Risk-free interest rate   0.28% 0.67%
Expected life (in years)   8 months 16 days 1 year 2 months 16 days
Dividend yield   0.00% 0.00%
Volatility   51.00% 49.00%
Stock price   $ 4.04 $ 3.18
February 2015 Warrants      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Risk-free interest rate 1.52% 1.52%  
Expected life (in years) 5 years 4 years 7 months 21 days  
Dividend yield 0.00% 0.00%  
Volatility 50.00% 50.00%  
Stock price $ 4.26 $ 4.04