Available-for-Sale Debt and Equity Investments - Summary of Available-for-sale Debt Investments and Equity Investments (Details) - USD ($) $ in Millions	Jul. 25, 2020	Jul. 27, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale debt investments	$ 17,610	$ 21,660
Marketable equity securities	0	3
Total investments	17,610	21,663
Non-marketable equity securities included in other assets	1,207	1,113
Equity method investments included in other assets	71	87
Total	$ 18,888	$ 22,863