Goodwill and Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 25, 2014	Apr. 26, 2013	Apr. 27, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 59.1	$ 85.8	$ 89.0
Cost of revenues | Developed Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	57.1	55.9	55.8
Operating expenses | Customer Contracts/Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	1.0	25.2	28.1
Operating expenses | Trademarks And Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	0.5	4.0	4.2
Operating expenses | Covenants not to Compete
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 0.5	$ 0.7	$ 0.9