Schedule of Share-based Compensation, Stock Options, Activity (Details) (USD $)	9 Months Ended
	Jan. 31, 2015
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 1	$ 3,705,539
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 2	1.62
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 3	871,000
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 4	1.12
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 5	(334,731)
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 6	0.60
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 7	(481,225)
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 8	1.40
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 9	3,760,583
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 10	1.62
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 11	1,916,875
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 12	1.79
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 13	$ 1,767,621
Common Stock Schedule Of Share-based Compensation, Stock Options, Activity 14	1.60