Net Income per Share - Computation of Basic and Diluted Net Income Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 25, 2014	Jan. 24, 2014	Oct. 25, 2013	Jul. 26, 2013	Apr. 26, 2013	Jan. 25, 2013	Oct. 26, 2012	Jul. 27, 2012	Apr. 25, 2014	Apr. 26, 2013	Apr. 27, 2012
Computation Of Earnings Per Share [Line Items]
Net income	$ 197.0	$ 192.1	$ 166.8	$ 81.6	$ 173.8	$ 158.1	$ 109.6	$ 63.8	$ 637.5	$ 505.3	$ 605.4
Shares used in basic computation									340.3	361.5	363.9
Dilutive potential shares related to employee equity award plans									6.9	5.4	8.8
Dilutive impact of assumed conversion of Convertible Notes									0.5	1.1	9.4
Dilutive impact of warrants									0.2	0	2.2
Shares used in diluted computation									347.9	368.0	384.3
Basic	$ 0.60	$ 0.57	$ 0.49	$ 0.23	$ 0.48	$ 0.44	$ 0.30	$ 0.17	$ 1.87	$ 1.40	$ 1.66
Diluted	$ 0.59	$ 0.55	$ 0.48	$ 0.23	$ 0.47	$ 0.43	$ 0.30	$ 0.17	$ 1.83	$ 1.37	$ 1.58