Quarterly report pursuant to Section 13 or 15(d)

Stock Options and Warrants (Detail)

v3.20.1
Stock Options and Warrants (Detail) - USD ($)
 9 Months Ended 12 Months Ended
Feb. 29, 2020
May 31, 2019
Stock option and warrant activity    
Options and warrants outstanding, Number of Shares   178,591,849
Granted, Number of Shares 56,818,838  
Exercised, Number of Shares (59,546,851)  
Forfeited/expired/cancelled, Number of Shares (2,677,865)  
Options and warrants outstanding, Number of Shares 173,185,971  
Outstanding exercisable, Number of Shares 169,122,723  
Options and warrants outstanding, Weighted Average Exercise Price   $ 0.71
Granted, Weighted Average Exercise Price $ 0.46  
Exercised, Weighted Average Exercise Price 0.39  
Forfeited/expired/cancelled, Weighted Average Exercise Price 0.73  
Options and warrants outstanding, Weighted Average Exercise Price 0.65  
Outstanding exercisable, Weighted Average Exercise Price $ 0.66  
Options and warrants outstanding, Weighted Average Remaining Contractual Life in Years 3 years 11 months 8 days 3 years 9 months
Outstanding exercisable, Weighted Average Remaining Contractual Life in Years 3 years 9 months 7 days  
Options and warrants outstanding, Aggregate Intrinsic Value $ 69,328,476 $ 896,400
Outstanding exercisable, Aggregate Intrinsic Value $ 67,192,113