Derivatives and Hedging Activities - Schedule of Notional Value of Outstanding Foreign Currency Forward Contracts (Detail) (United States of America, Dollars, USD $) In Millions, unless otherwise specified	Oct. 24, 2014	Apr. 25, 2014
Cash Flow Hedging | Long
Derivative [Line Items]
Forward contracts, Notional Amount	$ 153.0	$ 122.6
Non Designated | Long
Derivative [Line Items]
Forward contracts, Notional Amount	303.4	389.9
Non Designated | Short
Derivative [Line Items]
Forward contracts, Notional Amount	$ 187.4	$ 155.5