Available-for-Sale Debt Investments and Equity Investments - Summary of Available-for-sale Debt Investments and Equity Investments (Details) - USD ($) $ in Millions	Oct. 26, 2019	Jul. 27, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale debt investments	$ 19,445	$ 21,660
Marketable equity securities	3	3
Total investments	19,448	21,663
Non-marketable equity securities included in other assets	1,151	1,113
Equity method investments included in other assets	66	87
Total	20,665	22,863
Debt Securities, Available-for-sale [Line Items]
Non-marketable equity securities included in other assets	1,151	1,113
Net Asset Value (NAV) | Private equity funds
Investments, Debt and Equity Securities [Abstract]
Non-marketable equity securities included in other assets	700	600
Debt Securities, Available-for-sale [Line Items]
Non-marketable equity securities included in other assets	$ 700	$ 600