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, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	$ (65)	$ (50)	$ (82)	$ (71)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	66	50	81	71
Equity Derivatives | Other income (loss), net
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	(12)	(39)	(47)	(42)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	12	39	47	42
Interest Rate Derivatives | Interest Expense
Hedge Underlying Gain Loss [Line Items]
Gains (losses) on derivative instruments	(53)	(11)	(35)	(29)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ 54	$ 11	$ 34	$ 29