Related Party Transactions (Details) (USD $)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Board member | Consulting agreement
Long-Term Incentive Awards
Amount paid to related party	$ 96,000	$ 172,000	$ 210,000
Vendor with common board member
Long-Term Incentive Awards
Purchase of materials			$ 3,433,000