Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 24, 2014	Oct. 25, 2013	Oct. 24, 2014	Oct. 25, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 14.5	$ 14.9	$ 29.0	$ 29.8
Cost of revenues | Developed Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	14.2	14.3	28.5	28.6
Operating expenses | Customer Contracts/Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	0.1	0.3	0.2	0.7
Operating expenses | Trademarks And Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	0.2	0.1	0.3	0.2
Operating expenses | Covenants not to Compete
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 0	$ 0.2	$ 0	$ 0.3