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		6 Months Ended
	Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019
Earnings Per Share [Abstract]
Net income	$ 2,878	$ 2,822	$ 5,804	$ 6,371
Weighted-average shares—basic (in shares)	4,242	4,470	4,244	4,517
Effect of dilutive potential common shares (in shares)	18	35	21	40
Weighted-average shares—diluted (in shares)	4,260	4,505	4,265	4,557
Net income per share—basic (in dollars per share)	$ 0.68	$ 0.63	$ 1.37	$ 1.41
Net income per share—diluted (in dollars per share)	$ 0.68	$ 0.63	$ 1.36	$ 1.40
Antidilutive employee share-based awards, excluded (in shares)	29	27	32	28