Stockholders' Equity - Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 46	$ 63	$ 149	$ 199
Cost of Product Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1	1	3	4
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	5	10	15
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	20	27	64	84
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	14	20	46	64
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 8	$ 10	$ 26	$ 32