Net Income Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 27, 2012	Jan. 28, 2011	Jan. 27, 2012	Jan. 28, 2011
Net Income Per Share [Line Items]
Net income	$ 119.6	$ 186.4	$ 424.7	$ 512.5
Shares used in basic computation	360.3	364.8	364.0	358.8
Dilutive potential shares related to employee equity award plans	7.6	14.7	9.1	15.3
Dilutive impact of assumed conversion of Notes	5.8	16.9	9.3	11.9
Dilutive impact of warrants	0	9.8	2.7	4.7
Shares used in diluted computation	373.7	406.2	385.1	390.7
Net Income per Share: Basic	$ 0.33	$ 0.51	$ 1.17	$ 1.43
Net Income per Share: Diluted	$ 0.32	$ 0.46	$ 1.10	$ 1.31
Percentage of reduction in dilutive effect of Notes when stock price increases			80.00%
Debt instrument convertible conversion price	$ 31.85		$ 31.85
Options And Restricted Stock Units [Member]
Net Income Per Share [Line Items]
Options and RSUs	13.5	1.0	10.9	2.8