Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings
Beginning Balance (shares) at Apr. 30, 2019		36,664,521
Beginning Balance at Apr. 30, 2019	$ 1,408,769	$ 15,600	$ 1,393,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	263,846		263,846
Dividends declared	(47,096)		(47,096)
Exercise of stock options (shares)		66,638
Exercise of stock options	2,958	$ 2,958
Stock-based compensation (shares)		75,166
Stock-based compensation (net of tax withholding on employee share-based awards)	14,728	$ 14,728
Ending Balance (shares) at Apr. 30, 2020		36,806,325
Ending Balance at Apr. 30, 2020	1,643,205	$ 33,286	1,609,919
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	312,900		312,900
Dividends declared	(49,091)		(49,091)
Exercise of stock options (shares)		40,189
Exercise of stock options	1,784	$ 1,784
Stock-based compensation (shares)		103,364
Stock-based compensation (net of tax withholding on employee share-based awards)	$ 23,881	$ 23,881
Ending Balance (shares) at Apr. 30, 2021	36,949,878	36,949,878
Ending Balance at Apr. 30, 2021	$ 1,932,679	$ 58,951	1,873,728
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	339,790
Dividends declared	$ (52,092)		(52,092)
Exercise of stock options (shares)	3,000	3,000
Exercise of stock options	$ 133	$ 133
Stock-based compensation (shares)		158,789
Stock-based compensation (net of tax withholding on employee share-based awards)	$ 20,328	$ 20,328
Ending Balance (shares) at Apr. 30, 2022	37,111,667	37,111,667
Ending Balance at Apr. 30, 2022	$ 2,240,838	$ 79,412	$ 2,161,426