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. 27, 2018	Oct. 28, 2017
Earnings Per Share [Abstract]
Net income	$ 3,549	$ 2,394
Weighted-average shares—basic (in shares)	4,565	4,959
Effect of dilutive potential common shares (in shares)	49	35
Weighted-average shares—diluted (in shares)	4,614	4,994
Net income (loss) per share—basic (in dollars per share)	$ 0.78	$ 0.48
Net income (loss) per share—diluted (in dollars per share)	$ 0.77	$ 0.48
Antidilutive employee share-based awards, excluded (in shares)	9	15