Net Income (Loss) per Share (Calculation of Basic and Diluted Net Income per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Apr. 28, 2018	Apr. 29, 2017	Apr. 28, 2018	Apr. 29, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ 2,691	$ 2,515	$ (3,693)	$ 7,185
Weighted-average shares—basic (in shares)	4,791	5,005	4,892	5,015
Effect of dilutive potential common shares (in shares)	53	40	0	41
Weighted-average shares—diluted (in shares)	4,844	5,045	4,892	5,056
Net income (loss) per share—basic (in dollars per share)	$ 0.56	$ 0.50	$ (0.76)	$ 1.43
Net income (loss) per share—diluted (in dollars per share)	$ 0.56	$ 0.50	$ (0.76)	$ 1.42