Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.20.4
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
 3 Months Ended 6 Months Ended
Nov. 30, 2020
Aug. 31, 2020
Nov. 30, 2019
Aug. 31, 2019
Nov. 30, 2020
Nov. 30, 2019
May 31, 2020
Summary Of Significant Accounting Policies [Line Items]              
Net loss $ (34,966,000) $ (30,832,000) $ (14,860,000) $ (16,164,000) $ (65,798,000) $ (31,024,000)  
Accumulated (deficit) (421,587,000)       (421,587,000)   $ (354,711,000)
Balance in excess of federally insured limits 29,200,000       29,200,000   $ 14,000,000.0
Impairment charges         0 $ 0  
Pre-launch inventory qualified for capitalization $ 0       $ 0    
Federal statutory income tax rate, percent         21.00% 21.00%