Annual report pursuant to Section 13 and 15(d)

Registered Direct Equity Offerings - Additional Information (Detail)

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Registered Direct Equity Offerings - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
May 22, 2018
Mar. 23, 2018
Feb. 01, 2018
Jan. 31, 2018
Jan. 30, 2018
Jan. 23, 2018
Nov. 30, 2017
Oct. 11, 2017
Sep. 08, 2017
Feb. 28, 2017
Jan. 31, 2017
Dec. 12, 2016
Sep. 30, 2016
May 31, 2018
May 31, 2017
May 31, 2016
Nov. 24, 2017
Sep. 21, 2015
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares   3,027,263                                
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        
Gross proceeds from issuance of common stock                           25,224,212 $ 19,133,755 $ 37,569,964    
Stock repurchased during period, value                           259,157   789,140    
Inducement interest related to convertible notes                           2,352,045   1,194,887    
Common stock issued                           $ 104,546        
Investor                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price                           $ 0.50        
Proceeds from issuance of common shares                           $ 1,600,000        
Common Stock                                    
Stockholders Equity Note [Line Items]                                    
Number of shares to be sold                           310,526        
Common stock issued                           $ 311        
Offer to Amend and Exercise                                    
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares                                 51,090,113  
Class of warrants, exercise price                                 $ 0.50  
Offer to Amend and Exercise | Minimum                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price                                 0.50  
Offer to Amend and Exercise | Maximum                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price                                 1.35  
Short-Term Convertible Notes                                    
Stockholders Equity Note [Line Items]                                    
Purchase price, per share       $ 0.50                            
Warrants to purchase common shares, shares       7,718,010                            
Class of warrants, exercise price       $ 0.75                            
Term of warrants       5 years                            
Number of shares to be sold       12,062,728                            
Gross proceeds from issuance of common stock       $ 6,000,000                            
Debt Instrument, maturity date       Jan. 31, 2018                            
Debt Instrument, face amount       $ 6,000,000                           $ 2,700,000
Debt Instrument, accrued interest       300,000                            
Long-term debt and capital lease obligations including current maturities       6,300,000                       3,981,050    
Stock repurchased during period, value       $ 259,000                       $ 789,000    
Percentage of warrants coverage     100.00% 50.00%                            
Conversion of Stock       $ 0.50 $ 0.75                          
Reinvestment of the principal amount per share       $ 0.50                            
2013 Convertible Notes | Investor | Detachable Common Stock Warrants                                    
Stockholders Equity Note [Line Items]                                    
Inducement interest related to convertible notes       $ 2,400,000                            
2013 Convertible Notes | Investor | Detachable Common Stock Warrants | Minimum                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price       $ 0.75                            
2013 Convertible Notes | Investor | Detachable Common Stock Warrants | Maximum                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price       $ 1.00                            
Placement Agent                                    
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares 315,200         245,681   150,461 213,573 453,652 122,799   1,066,667          
Class of warrants, exercise price $ 0.55         $ 0.55   $ 0.715 $ 0.825 $ 0.825 $ 0.825   $ 0.825          
Term of warrants 5 years         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% 8.00%   8.00%          
Placement Agent | Short-Term Convertible Notes                                    
Stockholders Equity Note [Line Items]                                    
Cash commission paid       $ 164,425                            
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          
Class of warrants, exercise price                       $ 1.00 $ 1.00          
Term of warrants                       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%          
Securities Purchase Agreement | Investor                                    
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares                         6,666,667          
Class of warrants, exercise price                         $ 1.00          
Term of warrants                         5 years          
Securities Purchase Agreement | Placement Agent                                    
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares                         1,066,667          
Class of warrants, exercise price                         $ 0.825          
Term of warrants                         5 years          
Subscription Agreements                                    
Stockholders Equity Note [Line Items]                                    
Number of shares to be sold 4,640,000         3,071,014   1,880,765 3,336,331 5,670,661 1,534,999              
Purchase price, per share $ 0.50         $ 0.50   $ 0.65 $ 0.75 $ 0.75 $ 0.75              
Warrants to purchase common shares, shares 4,640,000     7,718,010   3,071,014   940,380 1,668,163 2,835,323 767,498              
Class of warrants, exercise price $ 0.75     $ 0.75   $ 0.75   $ 0.75 $ 1.00 $ 1.00 $ 1.00              
Term of warrants 5 years     5 years   5 years   5 years 5 years 5 years 5 years              
Proceeds from issuance of common shares $ 2,100,000         $ 1,400,000   $ 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%              
Subscription Agreements | Offer to Amend and Exercise                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price                                 $ 0.50  
Subscription Agreements | Warrant Holders [Member] | Offer to Amend and Exercise | Common Stock                                    
Stockholders Equity Note [Line Items]                                    
Common stock issued   $ 556,678                                
Make-Whole Securities                                    
Stockholders Equity Note [Line Items]                                    
Number of shares to be sold             503,015                      
Warrants to purchase common shares, shares             251,504                      
Class of warrants, exercise price             $ 0.75                      
Term of warrants             5 years                      
Make-Whole Securities | Investor                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price                 $ 0.75                  
Make-Whole Securities | Waiver and Subscription Agreement                                    
Stockholders Equity Note [Line Items]                                    
Purchase price, per share               $ 0.65 0.75                  
Class of warrants, exercise price               0.75 1.00                  
Make-Whole Securities | Placement Agent                                    
Stockholders Equity Note [Line Items]                                    
Warrants to purchase common shares, shares             26,702             26,702        
Class of warrants, exercise price             $ 0.715   0.715                  
Term of warrants             5 years                      
Make-Whole Securities | Placement Agent | Waiver and Subscription Agreement                                    
Stockholders Equity Note [Line Items]                                    
Class of warrants, exercise price               $ 0.715 $ 0.825