Derivative Instruments - Schedule of Notional Amounts of Derivatives Outstanding (Details) - USD ($) $ in Millions	Jan. 25, 2020	Jul. 27, 2019
Derivative [Line Items]
Derivatives	$ 6,795	$ 8,754
Derivatives designated as hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
Derivatives	595	663
Derivatives designated as hedging instruments: | Interest rate derivatives
Derivative [Line Items]
Derivatives	2,500	4,500
Derivatives designated as hedging instruments: | Net investment hedging instruments
Derivative [Line Items]
Derivatives	272	309
Derivatives not designated as hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
Derivatives	2,798	2,708
Derivatives not designated as hedging instruments: | Total return swaps—deferred compensation
Derivative [Line Items]
Derivatives	$ 630	$ 574