Annual report pursuant to Section 13 and 15(d)

Convertible Instruments - Activity related to the 2019 Short-term Convertible Notes (Detail)

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Convertible Instruments - Activity related to the 2019 Short-term Convertible Notes (Detail) - Two Thousand And Nineteen Short Term Convertible Notes [Member] - USD ($)
$ in Thousands
2 Months Ended 3 Months Ended 12 Months Ended
Nov. 14, 2019
Nov. 30, 2019
May 31, 2020
May 31, 2019
Short-term Debt [Line Items]        
Face value of short-term convertible Notes     $ 5,460 $ 5,460
Unamortized discount       (1,470)
Unamortized issuance costs       (404)
Accrued interest converted into principal     154  
Note repayment   $ (700) (460)  
Note conversions into common stock $ (200)   (5,154)  
Carrying value, current $ 5,900   $ 5,200 $ 3,586