Comprehensive Income - AOCI Components (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 25, 2020	Apr. 27, 2019	Apr. 25, 2020	Apr. 27, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 35,533	$ 40,789	$ 33,571	$ 43,204
Other comprehensive income (loss)	(409)	214	(317)	121
Effect of adoption of accounting standards	3,729		3,729
Ending balance	35,708	36,804	35,708	36,804
Net Unrealized Gains (Losses) on Available-for-Sale Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			0	(310)
Other comprehensive income (loss) before reclassifications			169	382
(Gains) losses reclassified out of AOCI			(20)	18
Tax benefit (expense)			(12)	(59)
Other comprehensive income (loss)				341
Effect of adoption of accounting standards		(168)		(168)
Ending balance	137	(137)	137	(137)
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(14)
Other comprehensive income (loss) before reclassifications			14
(Gains) losses reclassified out of AOCI			1
Tax benefit (expense)			(1)
Ending balance	0		0
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(11)
Other comprehensive income (loss) before reclassifications				3
(Gains) losses reclassified out of AOCI				(1)
Tax benefit (expense)				0
Other comprehensive income (loss)				2
Effect of adoption of accounting standards		0		0
Ending balance		(9)		(9)
Cumulative Translation Adjustment and Actuarial Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(778)	(528)
Other comprehensive income (loss) before reclassifications			(472)	(224)
(Gains) losses reclassified out of AOCI			2	4
Tax benefit (expense)			2	(2)
Other comprehensive income (loss)				(222)
Effect of adoption of accounting standards		0		0
Ending balance	(1,246)	(750)	(1,246)	(750)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(700)	(1,110)	(792)	(849)
Other comprehensive income (loss) before reclassifications			(289)	161
(Gains) losses reclassified out of AOCI			(17)	21
Tax benefit (expense)			(11)	(61)
Other comprehensive income (loss)	(409)	214	(317)	121
Effect of adoption of accounting standards	(168)	(168)	(168)	(168)
Ending balance	$ (1,109)	$ (896)	$ (1,109)	$ (896)