Stockholders' Equity - Number and Value of Shares Netted for Employee Taxes (Detail) (Restricted Stock Units, USD $) In Millions, unless otherwise specified	12 Months Ended
Apr. 24, 2015	Apr. 25, 2014	Apr. 26, 2013
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld for taxes	1.5	1.5	1.3
Fair value of shares withheld	$ 56.8	$ 57.7	$ 40.9

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

No definition available.

Name:	us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration