Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - FV, SBC (Detail)

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Summary of Significant Accounting Policies - FV, SBC (Detail) - USD ($)
 12 Months Ended
May 31, 2021
May 31, 2020
May 31, 2019
May 31, 2018
Liability:        
Beginning Balance $ 0 $ 2,407,000 $ 1,324,000  
Ending Balance   0 2,407,000 $ 1,324,000
Forfeiture rate 0.00%      
Redemption Provision Embedded Derivative        
Liability:        
Warrants issued     2,750,000  
Fair value adjustments   (2,005,000) (745,000)  
Warrant Derivative Liability        
Liability:        
Warrants issued       4,360,000
Fair value adjustments   11,547,000 $ (922,000) (3,855,000)
Exercises   (11,949,000)    
Allotment to placement agent        
Liability:        
Warrants issued       $ 819,000
Level 1        
Assets:        
Assets fair value $ 0 0    
Liability:        
Liabilities fair value 0 0    
Level 2        
Assets:        
Assets fair value 0 0    
Liability:        
Liabilities fair value $ 0 0    
Level 3        
Assets:        
Assets fair value   0    
Liability:        
Liabilities fair value   $ 0