Available-for-Sale Debt Investments and Equity Investments - Summary of Available-for-sale Debt Investments and Equity Investments (Details) - USD ($) $ in Millions	Jul. 27, 2019	Jul. 28, 2018
Investments, Debt and Equity Securities [Abstract]
Available-for-sale debt investments	$ 21,660	$ 37,009
Marketable equity securities	3	605
Total investments	21,663	37,614
Non-marketable equity securities included in other assets	1,113	978
Equity method investments included in other assets	87	118
Total	22,863	38,710
Debt Securities, Available-for-sale [Line Items]
Non-marketable equity securities included in other assets	1,113	$ 978
Net Asset Value (NAV) | Private equity funds
Investments, Debt and Equity Securities [Abstract]
Non-marketable equity securities included in other assets	600
Debt Securities, Available-for-sale [Line Items]
Non-marketable equity securities included in other assets	$ 600