Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Antidilutive Securities (Detail)

v3.21.1
Summary of Significant Accounting Policies - Antidilutive Securities (Detail) - shares
shares in Thousands
9 Months Ended
Feb. 28, 2021
Feb. 29, 2020
Stock options, warrants & unvested restricted stock    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 68,857 173,186
Convertible Debt Securities [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 12,000 8,108
Convertible Preferred Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 32,159 28,387