Credit Concentration (Details)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Customer A [Member]
Credit Concentration [Line Items]
Percentage Of Customer Receivables	21.10%	26.50%
Percentage of revenue	35.70%	41.50%	38.70%
Customer B [Member]
Credit Concentration [Line Items]
Percentage Of Customer Receivables	21.10%	30.70%
Percentage of revenue	22.80%	26.00%	34.20%