Net Income per Share - Calculation of Basic and Diluted Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Oct. 24, 2020	Oct. 26, 2019
Earnings Per Share [Abstract]
Net income	$ 2,174	$ 2,926
Weighted-average shares—basic (in shares)	4,230	4,246
Effect of dilutive potential common shares (in shares)	14	27
Weighted-average shares—diluted (in shares)	4,244	4,273
Net income per share—basic (in dollars per share)	$ 0.51	$ 0.69
Net income per share—diluted (in dollars per share)	$ 0.51	$ 0.68
Antidilutive employee share-based awards, excluded (in shares)	35	11