Stock Incentive and Purchase Plans (Allocation of Share Based Compensation Costs by Type of Arrangement) (Details) (USD $)	12 Months Ended
	Apr. 26, 2013	Apr. 27, 2012	Apr. 29, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 11,683,249	$ 11,102,237	$ 6,365,003
Service-based stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,916,855	2,639,748	2,505,417
Service-based restricted stock and restricted stock unit awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	5,067,292	5,290,854	3,859,586
Performance-based restricted stock and restricted stock unit and market-based awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3,699,102	$ 3,171,635	$ 0