Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 25, 2013	Oct. 26, 2012	Oct. 25, 2013	Oct. 26, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 14.9	$ 21.5	$ 29.8	$ 42.9
Cost of revenues | Developed Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	14.3	14.0	28.6	27.9
Operating expenses | Customer Contracts/Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	0.3	6.3	0.7	12.6
Operating expenses | Trademarks And Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	0.1	1.0	0.2	2.0
Operating expenses | Covenants Not To Compete
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 0.2	$ 0.2	$ 0.3	$ 0.4