Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2015	Jul. 25, 2014
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 14	$ 15
Cost of revenues | Developed Technology
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	14	15
Operating expenses | Customer Contracts/Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 0	$ 0