Fair Value (Fair Value, Nonrecurring Measurement) (Details) - Fair Value, Measurements, Nonrecurring - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 27, 2019	Apr. 28, 2018	Apr. 27, 2019	Apr. 28, 2018
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Total gains (losses) for nonrecurring measurements	$ (3)	$ (18)	$ 3	$ (37)
Non-marketable equity securities and equity method investments
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Total gains (losses) for nonrecurring measurements	(3)	(17)	3	(56)
Purchased intangible assets (impaired)
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Total gains (losses) for nonrecurring measurements	0	(1)	0	(1)
Property held for sale—land and buildings
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Total gains (losses) for nonrecurring measurements	$ 0	$ 0	$ 0	$ 20