Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)	6 Months Ended
	Oct. 31, 2013 Y
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 1	1.31%
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 2	0.62%
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 3	78.94%
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 4	74.47%
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 5	3.7
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 6	3.7
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 7	0.00%
Common Stock Schedule Of Share-based Payment Award, Stock Options, Valuation Assumptions 8	0.00%