Stock-Based Compensation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 26, 2012	Oct. 28, 2011	Oct. 26, 2012	Oct. 28, 2011
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 49	$ 49	$ 85	$ 90
Income tax benefits	(14)	(15)	(24)	(26)
Total stock-based compensation expense, net of tax	35	34	61	64
Cost of Products Sold
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	4	4	7	7
Research and Development Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	10	9	17	16
Selling, General and Administrative Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	35	36	61	67
Stock Options
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	16	21	27	36
Restricted Stock Awards
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	30	25	51	47
Employee Stock Purchase Plan
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 3	$ 3	$ 7	$ 7