Comprehensive Income - Reclassification Out of Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income (loss), net	$ 70	$ 27	$ 82	$ 8
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)
Net income (loss)	2,878	2,822	5,804	6,371
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income (loss)	8	(8)	17	(13)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized gains and losses on available-for-sale investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income (loss), net	11	(5)	21	(11)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized gains and losses on cash flow hedging instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Revenue	(2)		(5)
Cost of sales	0		1
Operating expenses	0		2
Net income (loss)	(2)		(2)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized gains and losses on cash flow hedging instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Revenue		2		3
Cost of sales		(1)		(1)
Operating expenses		0		(1)
Net income (loss)		1		1
Reclassification out of Accumulated Other Comprehensive Income | Cumulative translation adjustment and actuarial gains and losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income (loss), net	$ (1)	$ (4)	$ (2)	$ (3)