Stockholders Equity - Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 25, 2014	Apr. 26, 2013	Apr. 27, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 273.0	$ 276.6	$ 257.6
Cost of Product Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	5.6	6.1	5.4
Cost of Service Revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	16.7	19.4	17.8
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	125.0	132.2	126.0
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	87.7	84.1	74.1
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 38.0	$ 34.8	$ 34.3