Financial Instruments (Derivatives Not Designated As Hedges) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jan. 26, 2020	Aug. 02, 2020	Jul. 28, 2019	Jul. 29, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		$ 8	$ 3	$ (24)
Foreign Exchange Forward Contracts [Member] | Cost Of Products Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		(1)	0	(1)
Foreign Exchange Forward Contracts [Member] | Other Expenses/Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		2	0	(1)
Commodity Derivative Contracts [Member] | Cost Of Products Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		12	6	(2)
Commodity Derivative Contracts [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		0	(1)	0
Deferred Compensation Derivative Contracts [Member] | General and Administrative Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives		(2)	(2)	(2)
Treasury Lock [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Gain) or Loss Recognized in Earnings on Derivatives	$ (3)	$ (3)	$ 0	$ (18)