Goodwill and Purchased Intangible Assets, Net - Amortization Expense for Purchased Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 25, 2019	Jan. 26, 2018	Jan. 25, 2019	Jan. 26, 2018
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 13	$ 14	$ 38	$ 41
Cost of revenues | Developed Technology
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	10	10	28	27
Operating expenses | Customer Contracts/Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	3	3	10	11
Operating expenses | Other Purchased Intangibles
Acquired Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 0	$ 1	$ 0	$ 3