Shareholders' Equity Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Beginning Balance	$ 409	$ 487
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Beginning Balance	(53)	6
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Beginning Balance	305	801
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance	661	1,294
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	(13)	(52)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	71	(50)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	114	(211)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	172	(313)
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Ending Balance	396	435
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance	18	(44)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Ending Balance	419	590
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	$ 833	$ 981