Goodwill and Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 26, 2018	Jan. 27, 2017	Jan. 26, 2018	Jan. 27, 2017
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 14	$ 13	$ 41	$ 35
Cost of revenues | Developed Technology
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	10	8	27	21
Operating expenses | Customer Contracts/Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	3	4	11	11
Operating expenses | Other Purchased Intangibles
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 1	$ 1	$ 3	$ 3