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		9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Net Earnings Per Share [Abstract]
Net income	$ 2,901	$ 2,057	$ 14,827	$ 4,568
Denominator for basic net earnings per common share - weighted-average shares	15,475,683	14,581,573	15,218,558	14,498,483
Stock options and restricted stock units	352,000	323,000	376,000	221,000
Denominator for diluted net earnings per common share - weighted-average shares and assumed conversions	15,827,666	14,904,524	15,595,342	14,719,441
Basic	$ 0.19	$ 0.14	$ 0.97	$ 0.32
Diluted	$ 0.18	$ 0.14	$ 0.95	$ 0.31