Quarterly report pursuant to Section 13 or 15(d)

Registered Direct Equity Offerings - Additional Information (Detail)

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Registered Direct Equity Offerings - Additional Information (Detail) - USD ($)
 1 Months Ended 6 Months Ended
Oct. 11, 2017
Sep. 08, 2017
Feb. 28, 2017
Jan. 31, 2017
Dec. 12, 2016
Sep. 30, 2016
Nov. 30, 2017
Stockholders Equity Note [Line Items]              
Proceeds from issuance of common shares             $ 8,990,000
Warrants issued included in closing costs             1,066,667
Fair value of placement agent warrants             $ 819,200
Proceeds allocated to financing expense             241,986
Issuance cost incurred             $ 577,214
Placement Agent              
Stockholders Equity Note [Line Items]              
Warrants to purchase common shares, shares 150,461 213,573 453,652 122,799   1,066,667 350,766
Class of warrants, exercise price $ 0.715 $ 0.825 $ 0.825 $ 0.825   $ 0.825 $ 0.825
Term of warrants 5 years 5 years 5 years 5 years   5 years 5 years
Percentage of shares, issued as warrants 8.00% 8.00% 8.00% 8.00%   8.00%  
Securities Purchase Agreement              
Stockholders Equity Note [Line Items]              
Number of shares to be sold         4,000,000 13,333,334  
Purchase price, per share         $ 0.75 $ 0.75  
Warrants to purchase common shares, shares         2,000,000 6,666,667 3,258,990
Class of warrants, exercise price         $ 1.00 $ 1.00 $ 1.00
Term of warrants         5 years 5 years 5 years
Proceeds from issuance of common shares         $ 3,000,000 $ 9,000,000  
Placement agent's fees, as a percentage of gross proceeds           8.00%  
Subscription Agreements              
Stockholders Equity Note [Line Items]              
Number of shares to be sold 1,880,765 3,336,331 5,670,661 1,534,999      
Purchase price, per share $ 0.65 $ 0.75 $ 0.75 $ 0.75      
Warrants to purchase common shares, shares 940,380 1,668,163 2,835,323 767,498      
Class of warrants, exercise price $ 0.75 $ 1.00 $ 1.00 $ 1.00      
Term of warrants 5 years 5 years 5 years 5 years      
Proceeds from issuance of common shares $ 1,100,000 $ 2,300,000 $ 3,800,000 $ 1,000,000      
Placement agent's fees, as a percentage of gross proceeds   9.00% 9.00% 9.00%