Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.5.0.2
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
 12 Months Ended
May 31, 2016
May 31, 2015
Mar. 18, 2016
May 31, 2010
Apr. 30, 2010
Summary Of Significant Accounting Policies [Line Items]          
Common stock, par value $ 0.001 $ 0.001      
Net loss $ (25,703,612) $ (25,088,070)      
Accumulated (deficit) (97,225,914) (71,522,302)      
Balance in excess of federally insured limits 9,392,000 1,164,000      
Impairment charges 0 0      
Pre-launch inventory qualified for capitalization $ 0 $ 0      
Estimated future unvested forfeitures 0.00%        
Common stock, shares authorized 250,000,000 100,000,000     100,000,000
Direct costs associated with the convertible notes   $ 709,000      
Amortization of debt issuance costs $ 604,625 $ 103,598      
Common stock options and warrants to purchase 63,307,150 31,008,915      
Unrecognized benefits $ 0        
Reclassification Adjustment          
Summary Of Significant Accounting Policies [Line Items]          
Common stock, par value $ 0.001 $ 0.001      
Preferred stock, par value $ 0.001 $ 0.001      
Equity Securities          
Summary Of Significant Accounting Policies [Line Items]          
Deferred offering costs $ 3,900,000        
Short-Term Convertible Notes          
Summary Of Significant Accounting Policies [Line Items]          
Amortization of debt issuance costs $ 605,000 $ 104,000      
Before Amendment          
Summary Of Significant Accounting Policies [Line Items]          
Common stock, shares authorized     200,000,000    
After amendment          
Summary Of Significant Accounting Policies [Line Items]          
Common stock, shares authorized     250,000,000    
Series B Convertible Preferred Stock          
Summary Of Significant Accounting Policies [Line Items]          
Common stock, par value       $ 0.001  
Preferred stock, par value $ 0.001 $ 0.001   $ 0.001  
Preferred Stock Shares authorized to be issued 400,000 400,000      
Common stock options and warrants to purchase 95,100 95,100      
Common shares issued upon conversion of preferred stock 951,000        
Minimum          
Summary Of Significant Accounting Policies [Line Items]          
Income tax examination, year under examination 2012        
Maximum          
Summary Of Significant Accounting Policies [Line Items]          
Preferred Stock Shares authorized to be issued 5,000,000