Supplementary Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Selected Quarterly Financial Information [Abstract]
Revenue	$ 13,428	$ 12,958	$ 12,446	$ 13,072	$ 12,844	$ 12,463	$ 11,887	$ 12,136	$ 51,904	$ 49,330	$ 48,005
Gross margin	8,574	8,173	7,773	8,146	7,922	7,759	7,498	7,427	32,666	30,606	30,224
Operating income	3,690	3,513	3,211	3,805	3,346	3,134	3,073	2,756	14,219	12,309	11,973
Net income	$ 2,206	$ 3,044	$ 2,822	$ 3,549	$ 3,803	$ 2,691	$ (8,778)	$ 2,394	$ 11,621	$ 110	$ 9,609
Net income per share—basic (in dollars per share)	$ 0.52	$ 0.70	$ 0.63	$ 0.78	$ 0.81	$ 0.56	$ (1.78)	$ 0.48	$ 2.63	$ 0.02	$ 1.92
Net income per share—diluted (in dollars per share)	0.51	0.69	0.63	0.77	0.81	0.56	(1.78)	0.48	2.61	0.02	1.90
Cash dividends declared per common share (in dollars per share)	$ 0.35	$ 0.35	$ 0.33	$ 0.33	$ 0.33	$ 0.33	$ 0.29	$ 0.29	$ 1.36	$ 1.24	$ 1.1
Cash and cash equivalents and investments	$ 33,413	$ 34,643	$ 40,383	$ 42,593	$ 46,548	$ 54,431	$ 73,683	$ 71,588	$ 33,413	$ 46,548
Tax Cuts and Jobs Act, reversal of previously reported benefit	$ 872
Tax Cuts and Jobs Act, transition tax for accumulated foreign earnings, income tax benefit					$ (863)		9,000			863
Tax Cuts and Jobs Act of 2017, provisional tax expense							11,100			$ 10,400
Tax Cuts and Jobs Act of 2017, tax expense for foreign withholding tax							1,200
Tax Cuts and Jobs Act of 2017, re-measurement of net deferred tax assets							$ 900