Segment Information (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Apr. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reportable segments			2
Revenues	$ 6,652,000	$ 7,736,000	$ 13,315,000	$ 15,700,000
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	3,900,000	5,000,000	8,100,000	10,500,000
Long-lived assets	18,000,000		18,000,000		18,800,000
All Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	2,800,000	2,700,000	5,200,000	5,200,000
Long-lived assets	$ 0		$ 0		$ 0