Earnings Per Share (Schedule Of Earnings (Loss) Per Share, Basic And Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 58,763	$ 74,861	$ 83,688
Denominator for basic earnings per common share - weighted-average shares	16,970	16,908	17,289
Stock options and restricted stock units	67	44	41
Denominator for diluted earnings (loss) per common share - weighted-average shares and assumed conversions	17,037	16,952	17,330
Net earnings per share, Basic (usd per share)	$ 3.46	$ 4.43	$ 4.84
Net earnings per share, Diluted (usd per share)	$ 3.45	$ 4.42	$ 4.83