Acquisitions and Divestitures (Additional Information) (Details) $ in Millions	3 Months Ended
	Oct. 27, 2018 USD ($) acquisition	Oct. 28, 2017 USD ($)
Supplementary Information [Line Items]
Number of business combinations (acquisition) | acquisition	2
Acquired cash and cash equivalents	$ 82
Gains recognized from acquisitions	3	$ 46
Discontinued Operations, Held-for-sale | Service Provider Video
Supplementary Information [Line Items]
Disposal group, tangible assets	165
Disposal group, goodwill and intangible assets	330
Disposal group, liabilities	290
General and administrative
Supplementary Information [Line Items]
Acquisition related costs	$ 10	$ 9