Stockholders' Equity (Stock-Based Compensation Expense) (Details) (USD $) In Millions	3 Months Ended
	Jul. 29, 2011	Jul. 30, 2010
Total stock-based compensation expense	$ 58.1	$ 44.3
Cost Of Product Revenues [Member]
Total stock-based compensation expense	1.1	0.9
Cost Of Service Revenues [Member]
Total stock-based compensation expense	3.9	3.9
Sales And Marketing [Member]
Total stock-based compensation expense	28.6	20.6
Research And Development [Member]
Total stock-based compensation expense	16.0	11.1
General And Administrative [Member]
Total stock-based compensation expense	$ 8.5	$ 7.8