Fair Value, Assets Measured on Recurring Basis (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jul. 31, 2015	Apr. 30, 2015
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 1	$ 2,214,621
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 2	2,214,621
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 3	1
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 4	3,068,218
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 5	3,068,218
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 6	2
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 7	(39,615)
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 8	(39,615)
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 9	$ 2
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 1		$ 2,852,422
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 2		2,852,422
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 3		1
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 4		3,305,466
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 5		3,305,466
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 6		$ 2