Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail)

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Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
March 2011 Warrants    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate   0.16%
Expected life (in years)   2 months 16 days
Dividend yield   0.00%
Volatility   179.00%
Stock price   $ 0.48
February 2015 Warrants    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Risk-free interest rate 1.93% 1.76%
Expected life (in years) 3 years 1 month 17 days 4 years 1 month 21 days
Dividend yield 0.00% 0.00%
Volatility 135.00% 112.00%
Stock price $ 0.44 $ 0.48