Available-for-Sale Debt Investments and Equity Investments (Additional Information) (Details)	3 Months Ended		9 Months Ended
	Apr. 27, 2019 USD ($) entity	Apr. 28, 2018 USD ($)	Apr. 27, 2019 USD ($) entity	Apr. 28, 2018 USD ($)	Jul. 28, 2018 USD ($)
Schedule of Investments [Line Items]
Impairment charges of available-for-sale investments	$ 0	$ 0	$ 0	$ 0
Average daily balance of securities lending			$ 1,300,000,000	$ 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		$ 0
Number of variable interest entities required to be consolidated (entity) | entity	0		0
Investments in privately held companies	$ 1,300,000,000		$ 1,300,000,000
Funding commitments	345,000,000		345,000,000
Variable Interest Entity, Not Primary Beneficiary
Schedule of Investments [Line Items]
Investments in privately held companies	$ 683,000,000		$ 683,000,000