Comprehensive Income (Loss) - AOCI Components (Details) - USD ($) $ in Millions	6 Months Ended
	Jan. 23, 2021	Jan. 25, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 37,920	$ 33,571
Other comprehensive income (loss) before reclassifications	305	126
(Gains) losses reclassified out of AOCI	(27)	(17)
Tax benefit (expense)	23	(17)
Ending balance	39,121	35,533
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(519)	(792)
Ending balance	(218)	(700)
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	(35)	168
(Gains) losses reclassified out of AOCI	(24)	(21)
Tax benefit (expense)	24	(17)
Ending balance	280	130
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	(5)	0
(Gains) losses reclassified out of AOCI	(5)	2
Tax benefit (expense)	2	1
Ending balance	(14)	(11)
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	345	(42)
(Gains) losses reclassified out of AOCI	2	2
Tax benefit (expense)	(3)	(1)
Ending balance	$ (484)	$ (819)