Derivative Instruments (Derivatives Recorded At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Jan. 26, 2013	Jul. 28, 2012
Derivative [Line Items]
Derivative assets	$ 244	$ 264
Derivative liabilities	57	42
Designated As Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	228	247
Derivative liabilities	45	30
Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative assets	16	17
Derivative liabilities	12	12
Foreign Exchange Contract [Member] | Designated As Hedging Instrument [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	34	24
Foreign Exchange Contract [Member] | Designated As Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	2	26
Foreign Exchange Contract [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	16	16
Foreign Exchange Contract [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	12	12
Equity Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	0
Equity Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	43	4
Equity Derivatives [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative assets	0	1
Interest Rate Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative assets	$ 194	$ 223