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, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 22,024	$ 18,409	$ 18,488	$ 24,767	$ 19,109	$ 1,996	$ 19,755	$ 22,281	$ 83,688	$ 63,141	$ 71,199
Denominator for basic earnings per common share - weighted-average shares									17,289	16,631	16,259
Stock options and restricted stock units									41	114	139
Denominator for diluted earnings (loss) per common share - weighted-average shares and assumed conversions									17,330	16,745	16,398
Net earnings per share, Basic (usd per share)	$ 1.31	$ 1.07	$ 1.05	$ 1.41	$ 1.09	$ 0.12	$ 1.22	$ 1.37	$ 4.84	$ 3.80	$ 4.38
Net earnings per share, Diluted (usd per share)	$ 1.30	$ 1.07	$ 1.05	$ 1.41	$ 1.08	$ 0.12	$ 1.21	$ 1.36	$ 4.83	$ 3.77	$ 4.34