Derivative Instruments (Schedule of Notional Amounts of Derivatives Outstanding) (Details) - USD ($)	Jan. 27, 2018	Jul. 29, 2017
Derivative [Line Items]
Derivatives	$ 11,720,000,000	$ 11,590,000,000
Derivatives designated as hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
Derivatives	792,000,000	1,696,000,000
Derivatives designated as hedging instruments: | Interest rate derivatives
Derivative [Line Items]
Derivatives	6,750,000,000	6,750,000,000
Derivatives designated as hedging instruments: | Net investment hedging instruments
Derivative [Line Items]
Derivatives	214,000,000	351,000,000
Derivatives designated as hedging instruments: | Equity derivatives
Derivative [Line Items]
Derivatives	302,000,000	0
Derivatives not designated as hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
Derivatives	3,072,000,000	2,258,000,000
Derivatives not designated as hedging instruments: | Total return swaps—deferred compensation
Derivative [Line Items]
Derivatives	$ 590,000,000	$ 535,000,000