Available-for-Sale Debt Investments and Equity Investments - Additional Information (Details)	12 Months Ended
	Jul. 27, 2019 USD ($) entity	Jul. 28, 2018 USD ($)	Jul. 29, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract]
Impairment charges of available-for-sale investments	$ 0	$ 52,000,000	$ 74,000,000
Average daily balance of securities lending	$ 1,100,000,000	300,000,000
Fair value of securities received as collateral that can be resold or repledged, percentage (at least)	102.00%
Secured lending transactions outstanding	$ 0	$ 0
Number of variable interest entities required to be consolidated (entity) | entity	0
Schedule of Investments [Line Items]
Investments in privately held companies	$ 1,200,000,000
Funding commitments	326,000,000
Variable Interest Entity, Not Primary Beneficiary
Schedule of Investments [Line Items]
Investments in privately held companies	$ 656,000,000