Stock-Based Compensation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 24, 2014	Oct. 25, 2013	Oct. 24, 2014	Oct. 25, 2013
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 48	$ 44	$ 82	$ 75
Income tax benefits	(14)	(13)	(23)	(21)
Total stock-based compensation expense, net of tax	34	31	59	54
Cost of Products Sold
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	4	4	8	7
Research and Development Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	9	8	15	14
Selling, General and Administrative Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	35	32	59	54
Stock Options
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	14	13	20	20
Restricted Stock Awards
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	31	28	54	48
Employee Stock Purchase Plan
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 3	$ 3	$ 8	$ 7