Financial Instruments (Schedule of Cash Flow Hedges in Statements of Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 26, 2020	Jan. 31, 2021	Jan. 26, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Cost of products sold	$ 1,496	$ 1,420	$ 3,023	$ 2,865
Interest expense	55	149	110	229
Earnings from discontinued operations	0	1,037	0	1,034
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net	0	0	0	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net		0		0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cost Of Products Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net	0	0	0	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cost of products sold	2	(1)	2	(1)
Earnings from discontinued operations	0	0	0	(1)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ 1	$ 0	$ 1	$ 1