Income Taxes - Income Before Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 24, 2020	Oct. 26, 2019
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 2,681	$ 3,686
Provision for income taxes	$ 507	$ 760
Effective tax rate	18.90%	20.60%