Income Taxes - Income Before Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 3,534	$ 3,343	$ 7,220	$ 7,252
Provision for income taxes	$ 656	$ 521	$ 1,416	$ 881
Effective tax rate	18.60%	15.60%	19.60%	12.10%