Stockholders Equity - Income Tax Effects Associated with Employee Stock Transactions (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Oct. 24, 2014	Oct. 25, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit associated with employee stock transactions	$ 58.2	$ 1.8

Amount of increase (decrease) in additional paid in capital (APIC) resulting from a tax benefit (deficiency) associated with an share-based compensation plan other than an employee stock ownership plan (ESOP).

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration