Stockholders Equity - Activity Related to Stock Options (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
	Oct. 24, 2014
Number of Shares
Beginning balance, Number of Shares	14.5
Options granted, Number of Shares	2.1
Options exercised, Number of Shares	(2.5)
Options forfeited and expired, Number of Shares	(0.4)
Ending balance, Number of Shares	13.7
Options vested and expected to vest, Number of Shares	13.1
Options Exercisable, Number of Shares	9.0
Weighted-Average Exercise Price
Beginning balance, Weighted-Average Exercise Price	$ 34.10
Options granted, Weighted-Average Exercise Price	$ 36.53
Options exercised, Weighted-Average Exercise Price	$ 25.55
Options forfeited and expired, Weighted-Average Exercise Price	$ 43.10
Ending balance, Weighted-Average Exercise Price	$ 35.82
Options vested and expected to vest, Weighted-Average Exercise Price	$ 35.78
Options Exercisable, Weighted-Average Exercise Price	$ 35.25
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Outstanding, Weighted-Average Remaining Contractual Term	3 years 9 months 15 days
Options vested and expected to vest, Weighted-Average Remaining Contractual Term	3 years 8 months 5 days
Exercisable, Weighted-Average Remaining Contractual Term	2 years 9 months
Outstanding, Aggregate Intrinsic Value	$ 96.3
Options vested and expected to vest, Aggregate Intrinsic Value	93.7
Exercisable, Aggregate Intrinsic Value	$ 75.3