Derivative Instruments - Consolidated Statements of Operations of Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019
Derivative [Line Items]
Revenue	$ 12,005	$ 12,446	$ 25,164	$ 25,518
Cost of sales	4,241	4,673	8,936	9,599
Operating expenses	4,384	4,562	9,269	8,903
Interest and other income (loss), net	154	132	261	236
Total gains (losses)	1	3	2	3
Interest rate derivatives
Derivative [Line Items]
Hedged items	7	(61)	(14)	(52)
Derivatives designated as hedging instruments	(6)	64	16	55
Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income	0		0
Amount of gains (losses) reclassified from AOCI to income		0		0
Revenue
Derivative [Line Items]
Total gains (losses)	(2)	2	(5)	3
Revenue | Interest rate derivatives
Derivative [Line Items]
Hedged items	0	0	0	0
Derivatives designated as hedging instruments	0	0	0	0
Revenue | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income	(2)		(5)
Amount of gains (losses) reclassified from AOCI to income		2		3
Cost of sales
Derivative [Line Items]
Total gains (losses)	0	(1)	1	(1)
Cost of sales | Interest rate derivatives
Derivative [Line Items]
Hedged items	0	0	0	0
Derivatives designated as hedging instruments	0	0	0	0
Cost of sales | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income	0		1
Amount of gains (losses) reclassified from AOCI to income		(1)		(1)
Operating expenses
Derivative [Line Items]
Total gains (losses)	0	0	2	(1)
Operating expenses | Interest rate derivatives
Derivative [Line Items]
Hedged items	0	0	0	0
Derivatives designated as hedging instruments	0	0	0	0
Operating expenses | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income	$ 0		$ 2
Amount of gains (losses) reclassified from AOCI to income		$ 0		$ (1)