Segment Information (Narrative) (Details) (USD $)	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Apr. 30, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 9,638,000	$ 11,514,000
Contra expense	1,000,000
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	6,800,000	8,500,000
Long-Lived Assets	23,700,000		24,300,000
All Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	2,800,000	3,000,000
Long-Lived Assets	$ 4,000		$ 5,000