Earnings Per Share (Schedule Of Earnings (Loss) Per Share, Basic And Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 13,013	$ 12,804	$ 22,163	$ 26,881	$ 22,024	$ 18,409	$ 18,488	$ 24,767	$ 74,861	$ 83,688	$ 63,141
Denominator for basic earnings per common share - weighted-average shares									16,908	17,289	16,631
Stock options and restricted stock units									44	41	114
Denominator for diluted earnings (loss) per common share - weighted-average shares and assumed conversions									16,952	17,330	16,745
Net earnings per share, Basic (usd per share)	$ 0.77	$ 0.76	$ 1.31	$ 1.59	$ 1.31	$ 1.07	$ 1.05	$ 1.41	$ 4.43	$ 4.84	$ 3.80
Net earnings per share, Diluted (usd per share)	$ 0.77	$ 0.75	$ 1.31	$ 1.59	$ 1.30	$ 1.07	$ 1.05	$ 1.41	$ 4.42	$ 4.83	$ 3.77