Stock Incentive and Purchase Plans (Schedule of Stock Options Rollforward) (Details) (USD $)	3 Months Ended
	Jul. 26, 2013
Stock Incentive and Purchase Plans [Abstract]
Outstanding - beginning of period, shares	1,161,427
Granted, shares	241,805
Execised, shares	(118,457)
Forfeited, shares	(2,970)
Expired, shares	0
Outstanding - end of period, shares	1,281,805
Fully vested and exercisable - end of period, shares	665,515
Fully vested and expected to vest - end of period, shares	1,235,814
Weighted Average Exercise Price, beginning of period	$ 27.67
Weighted Average Exercise Price, Granted	$ 51.90
Weighted Average Exercise Price, Exercised	$ 21.55
Weighted Average Exercise Price, Forfeited	$ 39.68
Weighted Average Exercise Price, Expired	$ 0.00
Weighted Average Exercise Price, end of period	$ 32.78
Weighted Average Exercise Price, Fully vested and excercisable - end of period	$ 24.56
Weighted Average Exercise Price, Fully vested and expected to vest - end of period	$ 32.38
Weighted Average Remaining Contractual Term, Outstanding - end of period	6 years 11 months 5 days
Weighted Average Remaining Contractual Term - Fully vested and exercisable - end of period	5 years 18 days
Weighted Average Remaining Contractual Term - Fully vested and expected to vest - end of period	6 years 10 months 6 days
Aggregate Intrinsic Value, Outstanding - end of period	$ 25,944,726
Aggregate Intrinsic Value, Fully vested and exercisable - end of period	19,048,351
Aggregate Intrinsic Value, Fully vested and expected to vest - end of period	$ 25,514,147