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, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 13,372	$ 12,013	$ 18,180	$ 15,158	$ 11,308	$ 7,282	$ 7,671	$ 9,238	$ 58,723	$ 35,499	$ 20,461
Denominator for basic earnings per common share - weighted-average shares									16,256	15,764	15,299
Stock options and restricted stock units									186	273	354
Denominator for diluted earnings (loss) per common share - weighted-average shares and assumed conversions									16,442	16,037	15,653
Net earnings per share, Basic (usd per share)	$ 0.82	$ 0.74	$ 1.12	$ 0.94	$ 0.71	$ 0.46	$ 0.49	$ 0.59	$ 3.61	$ 2.25	$ 1.34
Net earnings per share, Diluted (usd per share)	$ 0.81	$ 0.73	$ 1.10	$ 0.92	$ 0.69	$ 0.45	$ 0.48	$ 0.59	$ 3.57	$ 2.21	$ 1.31