Goodwill and Purchased Intangible Assets (Schedule of Amortization of Purchased Intangible Assets) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 27, 2018	Jan. 28, 2017	Jan. 27, 2018	Jan. 28, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of purchased intangible assets	$ 60	$ 64	$ 121	$ 142
Cost of sales
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of purchased intangible assets	160	124	314	253
Amortization of purchased intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of purchased intangible assets	60	64	121	142
Restructuring and other charges
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of purchased intangible assets	0	0	0	38
Total
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of purchased intangible assets	$ 220	$ 188	$ 435	$ 433