Fair Value, Assets Measured on Recurring Basis (Details) (USD $)	6 Months Ended	12 Months Ended
	Oct. 31, 2013	Apr. 30, 2013
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 1	$ 9,423,773
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 2	9,423,773
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	3,585,191
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 5	3,585,191
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	(9,814)
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 8	(9,814)
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 9	3
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 10	0
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 11	0
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 12	3
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 1		11,229,595
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 2		11,229,595
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		4,640,620
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 5		4,640,620
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		9,830
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 8		9,830
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 9		3
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 10		93,057
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 11		93,057
Derivative Financial Instruments And Risk Management Fair Value, Assets Measured On Recurring Basis 12		$ 3