Employee Stock Benefit Plans (Summary Of Share-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 28, 2012	Jan. 29, 2011	Jan. 28, 2012	Jan. 29, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 354	$ 430	$ 695	$ 837
Cost Of Sales-Product [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	14	16	27	31
Cost Of Sales-Service [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	40	48	77	91
Share-Based Compensation Expense In Cost Of Sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	54	64	104	122
Research And Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	99	132	200	253
Sales And Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	149	167	291	331
General And Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	54	67	102	131
Restructuring And Other Charges [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	(2)		(2)
Share-Based Compensation Expense In Operating Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 300	$ 366	$ 591	$ 715