Derivative Instruments (Derivatives Recorded At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Jan. 25, 2014	Jul. 27, 2013
Derivative [Line Items]
Derivative assets	$ 164	$ 182
Derivative liabilities	53	171
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	152	180
Derivative liabilities	47	164
Designated as Hedging Instrument | Foreign Currency Derivatives | Other Current Assets
Derivative [Line Items]
Derivative assets	31	33
Designated as Hedging Instrument | Foreign Currency Derivatives | Other Current Liabilities
Derivative [Line Items]
Derivative liabilities	6	7
Designated as Hedging Instrument | Interest Rate Derivatives | Other Noncurrent Assets
Derivative [Line Items]
Derivative assets	121	147
Designated as Hedging Instrument | Interest Rate Derivatives | Other Noncurrent Liabilities
Derivative [Line Items]
Derivative liabilities	10	2
Designated as Hedging Instrument | Equity Derivatives | Other Current Assets
Derivative [Line Items]
Derivative assets	0	0
Designated as Hedging Instrument | Equity Derivatives | Other Current Liabilities
Derivative [Line Items]
Derivative liabilities	31	155
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Derivative assets	12	2
Derivative liabilities	6	7
Derivatives Not Designated As Hedging Instruments | Foreign Currency Derivatives | Other Current Assets
Derivative [Line Items]
Derivative assets	6	2
Derivatives Not Designated As Hedging Instruments | Foreign Currency Derivatives | Other Current Liabilities
Derivative [Line Items]
Derivative liabilities	6	7
Derivatives Not Designated As Hedging Instruments | Equity Derivatives | Other Noncurrent Assets
Derivative [Line Items]
Derivative assets	6	0
Derivatives Not Designated As Hedging Instruments | Equity Derivatives | Other Noncurrent Liabilities
Derivative [Line Items]
Derivative liabilities	$ 0	$ 0