Earnings (Loss) Per Share (Schedule Of Earnings (Loss) Per Share) (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
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ (878)	$ (65)	$ (1,721)	$ 344
Dividends paid and payable on preferred stock		(101)	(66)	(302)
Net income (loss) available to common stockholders	$ (878)	$ (166)	$ (1,787)	$ 42
Weighted-average shares of common stock outstanding, basic	16,384,000	14,718,000	16,022,000	14,718,000
Effect of dilutive securities				8,000
Weighted-average shares of common stock outstanding, diluted	16,384,000	14,718,000	16,022,000	14,726,000
Basic	$ (0.05)	$ (0.01)	$ (0.11)	$ 0.00
Diluted	$ (0.05)	$ (0.01)	$ (0.11)	$ 0.00
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of antidilutive securities	1,465,291	2,357,470	1,620,718	2,632,813
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of antidilutive securities	909,042	909,042	909,042	909,042
Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of antidilutive securities		1,666,667		1,666,667