Shareholders' Equity Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012
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	52	(59)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	65	(68)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	120	(317)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	237	(444)
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Ending Balance	461	428
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance	12	(62)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Ending Balance	425	484
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	$ 898	$ 850