Supplementary Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Selected Quarterly Financial Information [Abstract]
Revenue	$ 12,154	$ 11,983	$ 12,005	$ 13,159	$ 13,428	$ 12,958	$ 12,446	$ 13,072	$ 49,301	$ 51,904	$ 49,330
Gross margin	7,684	7,771	7,764	8,464	8,574	8,173	7,773	8,146	31,683	32,666	30,606
Operating income	3,247	3,414	3,380	3,579	3,690	3,513	3,211	3,805	13,620	14,219	12,309
Net income	$ 2,636	$ 2,774	$ 2,878	$ 2,926	$ 2,206	$ 3,044	$ 2,822	$ 3,549	$ 11,214	$ 11,621	$ 110
Net income per share—basic (in dollars per share)	$ 0.62	$ 0.66	$ 0.68	$ 0.69	$ 0.52	$ 0.70	$ 0.63	$ 0.78	$ 2.65	$ 2.63	$ 0.02
Net income per share—diluted (in dollars per share)	0.62	0.65	0.68	0.68	0.51	0.69	0.63	0.77	2.64	2.61	0.02
Cash dividends declared per common share (in dollars per share)	$ 0.36	$ 0.36	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.33	$ 0.33	$ 1.42	$ 1.36	$ 1.24
Cash and cash equivalents and investments	$ 29,419	$ 28,574	$ 27,062	$ 28,035	$ 33,413	$ 34,643	$ 40,383	$ 42,593	$ 29,419	$ 33,413
Tax Cuts and Jobs Act, reversal of previously reported benefit					$ 872