Financial Information by Geographic Location (Details) - USD ($)	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	$ 4,915,000	$ 7,338,000
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	3,262,000	6,113,000
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	1,143,000	1,116,000
Other (principally Asia Pacific Region)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	$ 510,000	$ 109,000