Stock-Based Compensation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 26, 2013	Jul. 27, 2012
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 31	$ 36
Income tax benefits	(8)	(10)
Total stock-based compensation expense, net of tax	23	26
Cost of Products Sold
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	3	3
Research and Development Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	6	7
Selling, General and Administrative Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	22	26
Stock Options
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	8	11
Restricted Stock Awards
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	19	21
Employee Stock Purchase Plan
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 4	$ 4