Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Computation of basic and diluted earnings per share of common stock
Net income	$ 27,219	$ 24,820
Less: Net income allocated to participating securities		319
Net income attributable to common stockholders	$ 27,219	$ 24,501
Basic earnings per common share:
Basic weighted average common shares outstanding (in shares)	42,624	41,001
Basic earnings per common share (in dollars per share)	$ 0.64	$ 0.60
Diluted earnings per common share:
Basic weighted average common shares outstanding (in shares)	42,624	41,001
Add: Common Stock Equivalents	393	614
Diluted weighted average common shares outstanding (in shares)	43,017	41,615
Diluted earnings per common share (in dollars per share)	$ 0.63	$ 0.59