Fair Value (Fair Value, Nonrecurring Measurement) (Details) - Fair Value, Measurements, Nonrecurring - Level 3 - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Gains (losses) for assets measured on a nonrecurring basis	$ (88)	$ (76)	$ (177)	$ (93)
Investments in privately held companies (impaired)
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Gains (losses) for assets measured on a nonrecurring basis	(64)	(39)	(111)	(56)
Purchased intangible assets (impaired)
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Gains (losses) for assets measured on a nonrecurring basis	0	(37)	(42)	(37)
Property held for sale—land and buildings
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Gains (losses) for assets measured on a nonrecurring basis	$ (24)	$ 0	$ (24)	$ 0