Comprehensive Income (Reclassified Out of Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013
Available-for-sale Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax			$ 165	$ 40
Available-for-sale Securities | Other income (loss), net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax	82	13	165	40
Derivative
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax	19	8	28	3
Derivative | Operating Expenses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax	16	6	23	2
Derivative | Cost Of Sales-Service
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax	3	2	5	1
Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amount Reclassified Out of OCI, Before Tax	$ 101	$ 21	$ 193	$ 43