Goodwill and Purchased Intangible Assets - Schedule of Amortization of Purchased Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 25, 2020	Jul. 27, 2019	Jul. 28, 2018
Acquired Intangible Asset Amortization by Statement of Operations Class [Line Items]
Amortization of purchased intangible assets	$ 141	$ 150	$ 221
Cost of sales
Acquired Intangible Asset Amortization by Statement of Operations Class [Line Items]
Amortization of purchased intangible assets	659	624	640
Operating expenses
Acquired Intangible Asset Amortization by Statement of Operations Class [Line Items]
Amortization of purchased intangible assets	141	150	221
Total
Acquired Intangible Asset Amortization by Statement of Operations Class [Line Items]
Amortization of purchased intangible assets	$ 800	$ 774	$ 861