Derivative Instruments (Effect Of Derivative Instruments Designated As Fair Value Hedges And Underlying Hedged Items On Consolidated Statements Of Operations Summary) (Details) (Derivatives Designated As Fair Value Hedging Instruments [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	$ 50	$ 41	$ 71	$ 76
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	50	(42)	71	(78)
Equity Contract [Member] | Other Income (loss), net [Member]
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	39	0	42	0
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	39	0	42	0
Interest Rate Contract [Member] | Interest Expense [Member]
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	11	41	29	76
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ 11	$ (42)	$ 29	$ (78)