Net Earnings Per Share (Schedule Of Earnings Per Share, Basic And Diluted) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 7,671	$ 5,271	$ 16,909	$ 11,926
Denominator for basic net earnings per common share - weighted-average shares	15,672,198	15,230,584	15,602,150	15,089,995
Stock options and restricted stock units	288,038	351,021	262,410	389,185
Denominator for diluted net earnings per common share - weighted-average shares and assumed conversions	15,960,236	15,581,605	15,864,560	15,479,180
Basic (usd per share)	$ 0.49	$ 0.35	$ 1.08	$ 0.79
Diluted (usd per share)	$ 0.48	$ 0.34	$ 1.07	$ 0.77