Derivatives and Hedging Activities - Schedule of Notional Value of Outstanding Foreign Currency Forward Contracts (Detail) - United States of America, Dollars - USD ($) $ in Millions	Jul. 31, 2015	Apr. 24, 2015
Cash Flow Hedging | Long
Derivative [Line Items]
Forward contracts, Notional Amount	$ 104	$ 94
Non Designated | Long
Derivative [Line Items]
Forward contracts, Notional Amount	290	231
Non Designated | Short
Derivative [Line Items]
Forward contracts, Notional Amount	$ 134	$ 160