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	Jan. 24, 2014	Apr. 26, 2013
Cash Flow Hedging | Long
Derivative [Line Items]
Forward contracts, Notional Amount	$ 188.8	$ 108.4
Non Designated | Long
Derivative [Line Items]
Forward contracts, Notional Amount	340.5	358.4
Non Designated | Short
Derivative [Line Items]
Forward contracts, Notional Amount	$ 148.4	$ 158.2