Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended						9 Months Ended
		Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Jan. 31, 2021	Jan. 31, 2020
Computation of basic and diluted earnings per share of common stock
Net income		$ 16,126	$ 28,469	$ 27,219	$ 10,879	$ 29,138	$ 24,820	$ 71,814	$ 64,837
Less: Net income allocated to participating securities									273
Net income attributable to common stockholders		$ 16,126			$ 10,879			$ 71,814	$ 64,564
Basic earnings per common share:
Basic weighted average common shares outstanding (in shares)		42,726			42,223			42,691	41,663
Basic earnings per common share (in dollars per share)	[1]	$ 0.38			$ 0.26			$ 1.68	$ 1.55
Diluted earnings per common share:
Basic weighted average common shares outstanding (in shares)		42,726			42,223			42,691	41,663
Add: Common Stock Equivalents		635			726			493	738
Diluted weighted average common shares outstanding (in shares)		43,361			42,949			43,184	42,401
Diluted earnings per common share (in dollars per share)	[1]	$ 0.37			$ 0.25			$ 1.66	$ 1.52
Shares were not included in the calculation of Diluted loss per common share
Anti-dilutive shares		300						400

[1] See Note 15 for detailed calculations.