Net Earnings (Loss) 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, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Earnings (Net Loss) Per Share [Abstract]
Net income (loss)	$ 2,057	$ (9,114)	$ 4,568	$ (14,806)
Denominator for basic net earnings (loss) per share - weighted-average shares	14,581,573	14,361,953	14,498,483	14,330,863
Stock options and restricted stock units	323,000	0	221,000	0
Denominator for diluted net earnings (loss) per share - weighted average shares and assumed conversions	14,904,524	14,361,953	14,719,441	14,330,863
Basic	$ 0.14	$ (0.63)	$ 0.32	$ (1.03)
Diluted	$ 0.14	$ (0.63)	$ 0.31	$ (1.03)