Derivative Instruments - Effect of Derivative Instruments on the Consolidated Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 25, 2020	Apr. 25, 2020	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018
Derivative [Line Items]
Revenue	$ 12,154	$ 11,983	$ 12,005	$ 13,159	$ 13,428	$ 12,958	$ 12,446	$ 13,072	$ 49,301	$ 51,904	$ 49,330
Cost of sales									17,618	19,238	18,724
Operating expenses									18,063	18,447	18,297
Interest and other income (loss), net									350	352	$ 730
Revenue
Derivative [Line Items]
Total gains (losses)									(1)	2
Revenue | Interest rate derivatives
Derivative [Line Items]
Hedged items									0	0
Derivatives designated as hedging instruments									0	0
Revenue | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income									(1)
Amount of gains (losses) reclassified from AOCI to income										2
Cost of sales
Derivative [Line Items]
Total gains (losses)									0	0
Cost of sales | Interest rate derivatives
Derivative [Line Items]
Hedged items									0	0
Derivatives designated as hedging instruments									0	0
Cost of sales | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income									0
Amount of gains (losses) reclassified from AOCI to income										0
Operating expenses
Derivative [Line Items]
Total gains (losses)									0	1
Operating expenses | Interest rate derivatives
Derivative [Line Items]
Hedged items									0	0
Derivatives designated as hedging instruments									0	0
Operating expenses | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income									0
Amount of gains (losses) reclassified from AOCI to income										1
Interest and other income (loss), net
Derivative [Line Items]
Total gains (losses)									3	7
Interest and other income (loss), net | Interest rate derivatives
Derivative [Line Items]
Hedged items									(98)	(138)
Derivatives designated as hedging instruments									101	145
Interest and other income (loss), net | Foreign currency derivatives
Derivative [Line Items]
Amount of gains (losses) reclassified from AOCI to income									$ 0
Amount of gains (losses) reclassified from AOCI to income										$ 0