Annual report pursuant to Section 13 and 15(d)

Public Warrant Tender Offers (Detail)

v3.21.2
Public Warrant Tender Offers (Detail)
$ / shares in Units, shares in Millions, $ in Millions
 2 Months Ended
Jul. 31, 2019
USD ($)
item
$ / shares
shares
May 31, 2021
$ / shares
Dec. 04, 2020
$ / shares
Oct. 14, 2020
$ / shares
May 31, 2020
$ / shares
May 31, 2019
$ / shares
Public Warrant Tender Offerings [Line Items]            
Stock price, in dollars per share   $ 1.50       $ 0.50
Common stock, par value $ 0.001 $ 0.001 $ 0.001 $ 0.001 $ 0.001  
Public Warrant Tender Offerings [Member]            
Public Warrant Tender Offerings [Line Items]            
Number of offerings | item 2          
Stock issued via offering, tender or placement, shares | shares 45.4          
Proceeds from issuance of common shares | $ $ 11.9          
Placement agent fees and expenses | $ 1.1          
Noncash inducement interest expense | $ $ 2.4          
Public Warrant Tender Offerings [Member] | Minimum            
Public Warrant Tender Offerings [Line Items]            
Stock price, in dollars per share $ 0.30          
Public Warrant Tender Offerings [Member] | Maximum            
Public Warrant Tender Offerings [Line Items]            
Stock price, in dollars per share $ 0.40