Stockholders' Equity - Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2015	Jul. 25, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 77	$ 62
Cost of Product Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	2	1
Cost of Hardware Maintenance and Other Services Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	6	5
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	31	27
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	26	21
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 12	$ 8