Purchased Intangible Assets, Net (Detail) (USD $) In Millions, unless otherwise specified	Oct. 25, 2013	Apr. 26, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Assets	$ 297.1	$ 379.2
Accumulated Amortization	(146.2)	(198.6)
Net Assets	150.9	180.6
Developed Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Assets	283.0	312.4
Accumulated Amortization	(134.0)	(134.9)
Net Assets	149.0	177.5
Customer Contracts/Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Assets	9.6	54.7
Accumulated Amortization	(8.7)	(53.1)
Net Assets	0.9	1.6
Trademarks And Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Assets	2.9	9.9
Accumulated Amortization	(2.2)	(8.9)
Net Assets	0.7	1.0
Covenants Not To Compete
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Assets	1.6	2.2
Accumulated Amortization	(1.3)	(1.7)
Net Assets	$ 0.3	$ 0.5