Comprehensive Income (Loss) - AOCI Components (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 24, 2020	Oct. 26, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 37,920	$ 33,571
Other comprehensive income (loss) before reclassifications	67	(6)
(Gains) losses reclassified out of AOCI	(17)	(9)
Tax benefit (expense)	22	(8)
Ending balance	38,157	34,423
Net Unrealized Gains (Losses) on Available-for-Sale Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	315	0
Other comprehensive income (loss) before reclassifications	(41)	87
(Gains) losses reclassified out of AOCI	(15)	(10)
Tax benefit (expense)	22	(9)
Ending balance	281	68
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(6)	(14)
Other comprehensive income (loss) before reclassifications	(2)	(1)
(Gains) losses reclassified out of AOCI	(2)	0
Tax benefit (expense)	1	1
Ending balance	(9)	(14)
Cumulative Translation Adjustment and Actuarial Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(828)	(778)
Other comprehensive income (loss) before reclassifications	110	(92)
(Gains) losses reclassified out of AOCI	0	1
Tax benefit (expense)	(1)	0
Ending balance	(719)	(869)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(519)	(792)
Ending balance	$ (447)	$ (815)