Quarterly report pursuant to Section 13 or 15(d)

Assumptions used in Estimating Fair Value of Warrant Derivative Liability (Detail)

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Assumptions used in Estimating Fair Value of Warrant Derivative Liability (Detail) - $ / shares
 6 Months Ended 12 Months Ended
Sep. 15, 2016
Nov. 30, 2019
May 31, 2019
Grant Date Fair Value      
Derivative [Line Items]      
Fair value of underlying stock $ 0.78 $ 0.28 $ 0.39
Risk Free Interest Rate      
Derivative [Line Items]      
Risk free rate 1.20% 1.61% 1.94%
Expected Term (In Years)      
Derivative [Line Items]      
Expected term (in years) 5 years 1 day 18 hours 2 years 3 months 14 days
Stock Price Volatility      
Derivative [Line Items]      
Stock price volatility 106.00% 63.00% 61.00%
Expected Dividend Yield      
Derivative [Line Items]      
Expected dividend yield 0.00% 0.00% 0.00%
Probability of Fundamental Transaction      
Derivative [Line Items]      
Probability of fundamental transaction 50.00% 50.00% 50.00%
Probability of Holder Requesting Cash Payment      
Derivative [Line Items]      
Probability of holder requesting cash payment 50.00% 50.00% 50.00%