Stockholders Equity - Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 26, 2012	Oct. 28, 2011	Oct. 26, 2012	Oct. 28, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 65.0	$ 63.0	$ 144.2	$ 121.1
Cost of Goods Sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1.5	1.4	3.3	2.5
Cost of Services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	4.6	4.2	10.2	8.1
Selling and Marketing Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	30.9	30.4	69.9	59.0
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	19.3	18.2	43.0	34.2
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 8.7	$ 8.8	$ 17.8	$ 17.3