Income Taxes (Income Before Provision for Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 3,343	$ 3,232	$ 7,252	$ 6,194
Provision for income taxes	$ 521	$ 12,010	$ 881	$ 12,578
Effective tax rate	15.60%	371.60%	12.10%	203.10%