Comprehensive Income (Loss) - Reclassification out of other comprehensive income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 27, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 28, 2018	Apr. 28, 2018	Jan. 27, 2018	Oct. 28, 2017	Jul. 27, 2019	Jul. 28, 2018	Jul. 29, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Revenue	$ 13,428	$ 12,958	$ 12,446	$ 13,072	$ 12,844	$ 12,463	$ 11,887	$ 12,136	$ 51,904	$ 49,330	$ 48,005
NET INCOME	$ 2,206	$ 3,044	$ 2,822	$ 3,549	$ 3,803	$ 2,691	$ (8,778)	$ 2,394	11,621	110	9,609
Total amounts reclassified out of AOCI									(12)	348	(182)
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									(13)	287	(87)
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	0	0
Cost of sales									0	16	(20)
Operating expenses									1	52	(59)
NET INCOME									3	68	(79)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income (loss), net									(2)	0	0
Operating expenses									$ 0	$ 7	$ 16