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. 26, 2019	Oct. 27, 2018
Earnings Per Share [Abstract]
Net income	$ 2,926	$ 3,549
Weighted-average shares—basic (in shares)	4,246	4,565
Effect of dilutive potential common shares (in shares)	27	49
Weighted-average shares—diluted (in shares)	4,273	4,614
Net income per share—basic (in dollars per share)	$ 0.69	$ 0.78
Net income per share—diluted (in dollars per share)	$ 0.68	$ 0.77
Antidilutive employee share-based awards, excluded (in shares)	11	9