Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Jan. 31, 2022	Jan. 31, 2021
Computation of basic and diluted earnings per share of common stock
Net income	$ 61,383	$ 74,361	$ 61,202	$ 16,126	$ 28,469	$ 27,219	$ 196,946	$ 71,814
Basic earnings per common share:
Basic weighted average common shares outstanding (in shares)	43,094			42,726			43,106	42,691
Basic earnings per common share (in dollars per share)	$ 1.42			$ 0.38			$ 4.57	$ 1.68
Diluted earnings per common share:
Basic weighted average common shares outstanding (in shares)	43,094			42,726			43,106	42,691
Add: Common Stock Equivalents (in shares)	851			635			831	493
Diluted weighted average common shares outstanding (in shares)	43,945			43,361			43,937	43,184
Diluted earnings per common share (in dollars per share)	$ 1.40			$ 0.37			$ 4.48	$ 1.66
Shares were not included in the calculation of Diluted loss per common share
Anti-dilutive shares (in shares)	0			300			0	400