Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.7.0.1
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 28, 2017
Feb. 29, 2016
Feb. 28, 2017
Feb. 29, 2016
May 31, 2015
Aug. 24, 2016
May 31, 2016
Mar. 18, 2016
Mar. 17, 2016
Apr. 30, 2010
Summary Of Significant Accounting Policies [Line Items]                    
Net loss $ (8,112,432) $ (5,046,835) $ (18,934,153) $ (19,206,442)            
Accumulated (deficit) (116,160,067)   (116,160,067)       $ (97,225,914)      
Balance in excess of federally insured limits 7,500,000   7,500,000       9,400,000      
Impairment charges 0 0 0 0            
Pre-launch inventory qualified for capitalization $ 0   $ 0       $ 0      
Estimated future unvested forfeitures     0.00%              
Common stock, shares authorized 350,000,000   350,000,000     350,000,000 250,000,000 250,000,000 200,000,000 100,000,000
Direct costs associated with the convertible notes     $ 0   $ 708,000          
Amortization of debt issuance costs       $ 604,625            
Common stock options and warrants to purchase     77,509,269 62,736,584            
Unrecognized benefits $ 0   $ 0              
Equity Securities                    
Summary Of Significant Accounting Policies [Line Items]                    
Deferred offering costs $ 1,800,000   $ 1,800,000       $ 3,900,000      
Short-Term Convertible Notes                    
Summary Of Significant Accounting Policies [Line Items]                    
Amortization of debt issuance costs   $ 0   $ 605,000            
Series B Convertible Preferred Stock                    
Summary Of Significant Accounting Policies [Line Items]                    
Preferred Stock Shares authorized to be issued 400,000   400,000       400,000      
Common stock options and warrants to purchase 92,100   92,100       95,100      
Common shares issued upon conversion of preferred stock     921,000              
Maximum                    
Summary Of Significant Accounting Policies [Line Items]                    
Preferred Stock Shares authorized to be issued 5,000,000   5,000,000              
Minimum                    
Summary Of Significant Accounting Policies [Line Items]                    
Income tax examination, year under examination     2012