Stockholders' Equity - Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 25, 2019	Jan. 26, 2018	Jan. 25, 2019	Jan. 26, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 43	$ 38	$ 121	$ 125
Income tax benefit for stock-based compensation expense	1	5	11	23
Cost of Product Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1	0	2	2
Cost of Hardware Maintenance and Other Services Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	3	3	8	8
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	19	16	52	53
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	13	11	37	38
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 7	$ 8	$ 22	$ 24