Derivative Instruments (Derivatives Recorded At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Oct. 27, 2012	Jul. 28, 2012
Derivative [Line Items]
Derivative assets	$ 274	$ 264
Derivative liabilities	55	42
Designated As Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	263	247
Derivative liabilities	23	30
Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative assets	11	17
Derivative liabilities	32	12
Foreign Exchange Contract [Member] | Designated As Hedging Instrument [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	47	24
Foreign Exchange Contract [Member] | Designated As Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	8	26
Foreign Exchange Contract [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	10	16
Foreign Exchange Contract [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	32	12
Equity Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	11
Equity Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	15	4
Equity Derivatives [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative assets	1	1
Interest Rate Derivatives [Member] | Designated As Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative assets	$ 205	$ 223