Quarterly report pursuant to Section 13 or 15(d)

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

v3.22.0.1
Stockholders' Equity - Summary of Stock Option Activity (Details)
9 Months Ended
Jan. 31, 2022
USD ($)
$ / shares
shares
Apr. 30, 2021
USD ($)
$ / shares
shares
Jan. 31, 2022
USD ($)
$ / shares
shares
Number of Shares      
Balance Outstanding, January 31, 2022 (in shares) 928,675   928,675
Exercisable, January 31, 2022 (in shares) 891,624   891,624
Stock Incentive Plan and Stock Option Grants to Employees and Directors      
Number of Shares      
Balance Outstanding, April 30, 2021 (in shares)     1,214,473
Granted (in shares)     0
Exercised (in shares)     (258,419)
Forfeited (in shares)     (4,586)
Expired (in shares)     (22,793)
Balance Outstanding, January 31, 2022 (in shares) 928,675 1,214,473 928,675
Exercisable, January 31, 2022 (in shares) 891,264   891,264
Weighted Average Exercise Price      
Balance Outstanding, April 30, 2021 (in dollars per share) | $ / shares     $ 6.24
Granted (in dollars per share) | $ / shares     0
Exercised (in dollars per share) | $ / shares     5.60
Forfeited (in dollars per share) | $ / shares     4.59
Expired (in dollars per share) | $ / shares     3.21
Balance Outstanding, January 31, 2022 (in dollars per share) | $ / shares $ 6.84 $ 6.24 6.84
Exercisable, January 31, 2022 (in dollars per share) | $ / shares $ 6.92   $ 6.92
Stock Option Activity, Additional Disclosures      
Options outstanding, weighted average remaining contractual term 1 year 4 months 28 days 1 year 10 months 17 days  
Options exercisable, weighted average remaining contractual term 1 year 4 months 17 days    
Options outstanding, aggregate intrinsic value | $ $ 0 $ 204,719 $ 0
Options exercisable, aggregate intrinsic value | $ $ 0   $ 0