Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Oct. 31, 2023	Jul. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Oct. 31, 2023	Oct. 31, 2022
Computation of basic and diluted earnings per share of common stock
Net income	$ 80,957	$ 86,830	$ 103,153	$ 89,470	$ 167,787	$ 192,623
Basic earnings per common share:
Basic weighted average common shares outstanding (in shares)	40,466		42,232		40,608	42,390
Basic earnings per common share (in dollars per share)	$ 2.00		$ 2.44		$ 4.13	$ 4.54
Diluted earnings per common share:
Basic weighted average common shares outstanding (in shares)	40,466		42,232		40,608	42,390
Add: Common Stock Equivalents (in shares)	622		655		674	712
Diluted weighted average common shares outstanding (in shares)	41,088		42,887		41,282	43,102
Diluted earnings per common share (in dollars per share)	$ 1.97		$ 2.41		$ 4.06	$ 4.47
Shares were not included in the calculation of Diluted loss per common share
Anti-dilutive shares (in shares)	0		0		0	0