Stockholders Equity - Schedule of Employee Stock Purchase Plan ESPP (Detail) (Employee Stock Purchase Plan, USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Jul. 27, 2012	Jul. 29, 2011
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per right granted	$ 10.25	$ 15.88
Shares issued under the ESPP	1.9	1.1
Weighted-average price per share issued	$ 25.30	$ 39.17