Fair Value Measurements (Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) (USD $)	9 Months Ended
Jan. 25, 2013	Jan. 27, 2012
Fair Value Measurements [Abstract]
Beginning Balance	$ 5,508,768	$ 5,209,590
Net purchases and settlements	0	0
Transfers in/(out) of Level 3	0	0
Interest accrual	0	224,384
Other-than-temporary impairment included in net income	(4,058,768)	0
Unrealized gains/(losses) included in other comprehensive income	0	0
Ending Balance	$ 1,450,000	$ 5,433,974

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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Amount of realized and unrealized gain (loss) included in earnings, which have arisen from the use of significant unobservable inputs (level 3) to measure fair value of assets, liabilities, and financial instruments classified in shareholders' equity.

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Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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