Stockholders' Equity (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended				0 Months Ended	1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended		12 Months Ended	1 Months Ended		12 Months Ended
	Jun. 30, 2011	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010	Jun. 30, 2013 Preferred Stock [Member]	Jun. 30, 2011 Preferred Stock [Member]	Apr. 30, 2012 Preferred Stock [Member]	Apr. 30, 2013 Preferred Stock [Member]	Jun. 30, 2010 Warrant [Member]	Apr. 30, 2011 2010 Stock Plan [Member]	Apr. 30, 2013 2010 Stock Plan [Member]	Apr. 30, 2011 2001 Option Plan [Member]	Jun. 30, 2011 Private Placement [Member] Preferred Stock [Member]	Apr. 30, 2004 Private Placement [Member] Warrant [Member]	Apr. 30, 2011 Minimum [Member] 2001 Option Plan [Member]
Subsidiary, Sale of Stock [Line Items]
Issued shares										718,860				1,666,667	190,182
Price per share of stock issued							$ 2.40			$ 2.45					$ 2.75
Stock issued during period, shares, new issues								1,666,667
Stock issued during period, value, new issues			$ 3,972,000	$ 7,958,000			$ 4,000,000	$ 2,000
Common shares converted from preferred shares						1,666,667
Preferred stock conversion basis						1-for-1	1
Average price of common stock to induce conversion	$ 4.00
Preferred stock conversion date	Jun. 30, 2013
Period used to calculate average price of common stock to induce conversion	30 days
Number of shares available for issuance									7,931,370		1,500,000
Share vesting period, years											4 years		4 years
Stock options granted, expiration period, years											10 years		10 years
Option purchase price, percentage of fair value																85.00%
Total intrinsic value of awards exercised		0	100,000	26,339
Fair value of awards vested		700,000	300,000	1,100,000
Fair value of awards granted		400,000	1,100,000	1,400,000
Options exercisable, number outstanding		1,367,834	1,627,079
Options exercisable, weighted-average exercise price		$ 3.15	$ 3.49
Shares reserved for future grants												646,119
Options outstanding, shares		1,814,599	2,632,115	2,152,183	1,663,497
Preferred stock annual dividend rate, percentage	10.00%
Dividend paid		$ 400,000	$ 300,000
Preferred stock dividend per share		$ 0.24	$ 0.20
Preferred stock, shares authorized		7,931,370	7,931,370
Common stock, shares authorized		40,000,000	40,000,000
Expected term (in years)		4 years	4 years	4 years