Fair Value Measurements (Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) (USD $)	12 Months Ended
	Apr. 26, 2013		Apr. 27, 2012		Apr. 29, 2011
Fair Value Measurements [Abstract]
Available-for-sale debt security	$ 0	[1]	$ 5,508,768	[1]	$ 5,209,590
Beginning Balance	5,508,768	[1]	5,209,590		0
Net purchases			0		5,000,000
Settlement of the NeuroVista note	(1,450,000)		0		0
Settlement	(1,450,000)		0		0
Interest accrual	0		299,178		209,590
Transfers in/(out) of Level 3	0		0		0
Other-than-temporary impairment included in net income	(4,058,768)		0		0
Total unrealized gains/(losses) included in other comprehensive income	0		0		0
Ending Balance	$ 0	[1]	$ 5,508,768	[1]	$ 5,209,590

[1] The available-for-sale convertible debt security was issued by NeuroVista Corporation (“NeuroVista”) on August 20, 2010. NeuroVista is a privately-held company that was focused on the development of an implantable device intended to inform patients when seizures are likely to occur, as well as to alert caregivers when seizures do occur. During the quarter ended July 27, 2012, we recorded an other-than-temporary impairment loss of $4.1 million based on our determination that the fair value of the investment was below our carrying value. In addition, during the quarter ended October 26, 2012, NeuroVista advised us that an event of default had occurred under the terms of the convertible debt security. We subsequently took possession of tangible and intangible assets in a foreclosure settlement of the note. We obtained assets fair valued at $1.45 million. See “Note 18. Fair Value Measurements” for further details regarding this investment.