Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summary of Stock Option Activity (Details)

v3.20.4
Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($)
3 Months Ended 6 Months Ended
Oct. 31, 2020
Apr. 30, 2020
Oct. 31, 2020
Oct. 31, 2020
Number of Shares        
Exercised (in shares)     (36,111)  
Balance Outstanding, October 31, 2020 (in shares) 1,744,354   1,744,354 1,744,354
Exercisable, October 31, 2020 (in shares) 1,439,330   1,439,330 1,439,330
Stock Incentive Plan and Stock Option Grants to Employees and Directors        
Number of Shares        
Balance Outstanding, April 30, 2020 (in shares)       2,740,539
Granted (in shares)     0 0
Exercised (in shares)       (989,767)
Forfeited (in shares)       (6,418)
Expired (in shares)       0
Balance Outstanding, October 31, 2020 (in shares)   2,740,539    
Exercisable, October 31, 2020 (in shares) 1,439,330   1,439,330 1,439,330
Weighted Average Exercise Price        
Balance Outstanding, April 30, 2020 (in dollars per share)       $ 4.62
Granted (in dollars per share)       0
Exercised (in dollars per share)       10.78
Forfeited (in dollars per share)       6.51
Expired (in dollars per share)       0
Balance Outstanding, October 31, 2020 (in dollars per share) $ 5.66 $ 4.62 $ 5.66 5.66
Exercisable, October 31, 2020 (in dollars per share) $ 5.66   $ 5.66 $ 5.66
Stock Option Activity, Additional Disclosures        
Options outstanding, weighted average remaining contractual term 1 year 11 months 26 days 1 year 11 months 19 days    
Options exercisable, weighted average remaining contractual term 1 year 9 months 14 days      
Options outstanding, aggregate intrinsic value $ 6,482,286 $ 9,146,198 $ 6,482,286 $ 6,482,286
Options exercisable, aggregate intrinsic value $ 5,495,787   $ 5,495,787 $ 5,495,787