Annual report pursuant to Section 13 and 15(d)

Convertible Instruments - Long-term Convertible Note - March 2020 Note (Detail)

v3.21.2
Convertible Instruments - Long-term Convertible Note - March 2020 Note (Detail)
$ / shares in Units, shares in Millions
1 Months Ended 3 Months Ended 12 Months Ended
Nov. 10, 2020
USD ($)
$ / shares
Mar. 31, 2020
USD ($)
item
agreement
$ / shares
shares
Jul. 27, 2020
USD ($)
$ / shares
shares
Nov. 30, 2020
USD ($)
May 31, 2021
USD ($)
agreement
item
$ / shares
shares
May 31, 2020
USD ($)
$ / shares
May 31, 2019
USD ($)
Dec. 04, 2020
$ / shares
Oct. 14, 2020
$ / shares
Jul. 31, 2019
$ / shares
Debt Instrument [Line Items]                    
Net Proceeds         $ 100,000,000 $ 15,000,000 $ 14,877,000      
Amortization of debt discount         3,591,000 1,645,000 1,707,000      
Interest on convertible notes         $ 4,387,000 $ 7,330,000 $ 950,000      
Shares issued on debt conversion | shares         19.9          
Common stock, par value | $ / shares         $ 0.001 $ 0.001   $ 0.001 $ 0.001 $ 0.001
Long-term Convertible Note-March 2020 Note                    
Debt Instrument [Line Items]                    
Debt instrument term   2 years                
Convertible note, aggregate principal   $ 17,100,000                
Net Proceeds   15,000,000.0                
Unamortized discount   $ 2,100,000                
Convertible notes, interest rate   10.00%                
Conversion price per share | $ / shares   $ 4.50 $ 4.50              
Debt instrument lock in period   6 months                
Number of days of notice to be given for conversion of notes into common stock   5 days                
Number of days of notice to be given for redemption   3 days                
Amortization of debt discount         $ 1,900,000 $ 200,000        
Interest on convertible notes         480,000          
Principal amount of debt converted     $ 9,500,000   9,538,000          
Shares issued on debt conversion | shares   4.3 2.1              
Cash paid to redeem debt       $ 950,000 950,000          
Number of exchange agreements | agreement   3                
Number of partitioned notes | item   3                
Carrying value of Note         0          
Loss on extinguishment of convertible notes         4,200,000          
Long-term Convertible Note-March 2020 Note | Maximum                    
Debt Instrument [Line Items]                    
Specified monthly redemption amount   $ 950,000                
Long-term Convertible Note - November 2020 Note                    
Debt Instrument [Line Items]                    
Debt instrument term 2 years                  
Convertible note, aggregate principal $ 28,500,000                  
Net Proceeds 25,000,000.0       25,000,000          
Unamortized discount $ 3,400,000                  
Convertible notes, interest rate 10.00%                  
Conversion price per share | $ / shares $ 10.00                  
Debt instrument lock in period 6 months                  
Number of days of notice to be given for conversion of notes into common stock 5 days                  
Number of days of notice to be given for redemption 3 days                  
Specified monthly redemption amount $ 7,500,000     $ 7,500,000            
Interest on convertible notes         $ 1,258,000          
Number of exchange agreements | agreement         2          
Number of partitioned notes | item         2          
Carrying value of Note         $ 13,600,000          
Loss on extinguishment of convertible notes         $ 6,400,000          
Long-term Convertible Note - November 2020 Note | Maximum                    
Debt Instrument [Line Items]                    
Specified monthly redemption amount $ 3,500,000