Shareholders' Equity - Additional Information (Details)	12 Months Ended
	Apr. 30, 2022 USD ($) segment $ / shares shares	Apr. 30, 2021 USD ($) $ / shares shares	Apr. 30, 2020 USD ($) $ / shares shares	Aug. 19, 2002 shares
Stock Based Compensation And Stockholders Equity [Line Items]
Number of stock option plans | segment	2
Options available for grant (in shares)	1,458,500
Weighted-average grant date fair value of stock options granted (in usd per share) | $ / shares	$ 6.86	$ 3.87	$ 3.20
Exercised (in shares)	776,129	628,917	1,020,910
Total intrinsic value of options exercised | $	$ 10,011,055	$ 4,229,040	$ 5,569,882
Fair value of grants vested | $	2,800,572	$ 2,206,610	$ 1,786,342
Unrecognized compensation cost related to unvested stock option | $	$ 11,500,000
Weighted average period for unrecognized compensation cost	1 year 10 months 20 days
Common stock shares repurchased	0
2020 Equity Compensation Plan
Stock Based Compensation And Stockholders Equity [Line Items]
Options available for grant (in shares)	6,250,000
Options exercisable period, maximum	6 years
Options authorized for issuance (in shares)	6,250,000
2020 Equity Compensation Plan | Non Qualified
Stock Based Compensation And Stockholders Equity [Line Items]
Options available for grant (in shares)	10,000
Incentive and nonqualified options exercisable (in shares)	1,315,604	900,610	1,086,180
2020 Equity Compensation Plan | Quarterly Option Amount
Stock Based Compensation And Stockholders Equity [Line Items]
Options available for grant (in shares)	4,000
Class B Common Shares
Stock Based Compensation And Stockholders Equity [Line Items]
Number of votes per share	1
Class A Common Shares
Stock Based Compensation And Stockholders Equity [Line Items]
Number of votes per share	0.10
Percentage of board of directors entitled to elect	25.00%
Ownership compared to both classes of common stock	10.00%
Common stock dividends declared (in usd per share) | $ / shares	$ 0.05
Common stock shares repurchased	4,588,632
Cost of common stock repurchased | $	$ 25,600,000
Class A Common Shares | Shares Stock Repurchase Plan, August 19, 2002
Stock Based Compensation And Stockholders Equity [Line Items]
Approved number of shares to be repurchased				2,000,000
Common stock shares repurchased	1,053,679
Cost of common stock repurchased | $	$ 6,200,000
Class A Common Shares | 2020 Equity Compensation Plan
Stock Based Compensation And Stockholders Equity [Line Items]
Common stock shares repurchased	2,902,643
Shareholder Holding More Than 10% of Outstanding Shares | 2020 Equity Compensation Plan
Stock Based Compensation And Stockholders Equity [Line Items]
Ownership compared to both classes of common stock	10.00%
Options exercisable period, maximum	5 years