Financial Information by Geographic Location (Details) (USD $)	3 Months Ended		9 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	$ 8,050,557us-gaap_Revenues	$ 7,641,079us-gaap_Revenues	$ 22,655,310us-gaap_Revenues	$ 22,418,038us-gaap_Revenues
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	6,913,663	6,246,904	19,243,219	18,562,000
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	1,017,452	830,553	3,015,695	2,359,604
Other (principally Asia Pacific Region)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues by geographic location	$ 119,442	$ 563,622	$ 396,396	$ 1,496,434