Other Intangible Assets Net - Other Intangible Assets Net (Detail) (USD $) In Millions, unless otherwise specified	Jul. 27, 2012	Apr. 27, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 348.8	$ 358.4
Accumulated Amortization	(134.2)	(122.4)
Other Intangible Assets, Net	214.6	236.0
Developed Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	282.1	282.1
Accumulated Amortization	(92.9)	(79.0)
Other Intangible Assets, Net	189.2	203.1
Customer Contracts/Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	54.6	59.4
Accumulated Amortization	(34.2)	(32.7)
Other Intangible Assets, Net	20.4	26.7
Trademarks And Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9.9	14.7
Accumulated Amortization	(5.9)	(9.7)
Other Intangible Assets, Net	4.0	5.0
Covenants Not To Compete
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2.2	2.2
Accumulated Amortization	(1.2)	(1.0)
Other Intangible Assets, Net	$ 1.0	$ 1.2