Derivatives and Hedging Activities - Schedule of Notional Value of Outstanding Foreign Currency Forward Contracts (Detail) (USD $) In Millions, unless otherwise specified	Oct. 26, 2012	Apr. 27, 2012
Euro
Derivative [Line Items]
Cash Flow Hedges	$ 142.4	$ 96.9
Balance Sheet Contracts	179.0	267.4
British Pound Sterling
Derivative [Line Items]
Cash Flow Hedges	39.6	29.8
Balance Sheet Contracts	76.2	86.4
Australian Dollar
Derivative [Line Items]
Balance Sheet Contracts	95.4	38.5
Canadian Dollar
Derivative [Line Items]
Balance Sheet Contracts	30.4	54.3
Swiss Franc
Derivative [Line Items]
Balance Sheet Contracts	24.8	7.3
Israeli Shekel
Derivative [Line Items]
Balance Sheet Contracts	24.4	17.2
Other
Derivative [Line Items]
Balance Sheet Contracts	$ 45.1	$ 44.0