Goodwill and Purchased Intangible Assets (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Purchased intangible assets impairment	$ 0	$ 37	$ 42	$ 37
Impairment charges	64	71	142	140
Restructuring and other charges
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment charges	$ 0	$ 0	$ 38	$ 0