Stock-Based Compensation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 24, 2014	Jan. 25, 2013	Jan. 24, 2014	Jan. 25, 2013
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 33	$ 34	$ 108	$ 119
Income tax benefits	(9)	(10)	(30)	(34)
Total stock-based compensation expense, net of tax	24	24	78	85
Cost of Products Sold
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	3	3	10	10
Research and Development Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	6	7	20	24
Selling, General and Administrative Expense
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	24	24	78	85
Stock Options
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	7	9	27	36
Restricted Stock Awards
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	24	23	72	74
Employee Stock Purchase Plan
Stock-based Compensation Expense by Component and Classification
Stock-based compensation expense	$ 2	$ 2	$ 9	$ 9