Cash and Cash Equivalents, Investments, and Funds Held for Customers - Table of cash and cash equivalents, investments, and funds held for customers by balance sheet classification (Details) - USD ($) $ in Millions	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Amortized Cost
Cash and cash equivalents	$ 2,562	$ 6,442	$ 2,116
Investments	1,504	800
Total cash and cash equivalents, investments, and funds held for customers	4,323	7,497
Fair Value
Investments	1,508	808
Total cash and cash equivalents, investments, and funds held for customers	4,327	7,505
Cash and cash equivalents
Amortized Cost
Cash and cash equivalents	2,562	6,442
Fair Value
Cash and cash equivalents	2,562	6,442
Investments
Amortized Cost
Investments	1,305	600
Fair Value
Investments	1,308	608
Funds held for customers
Amortized Cost
Investments	456	455
Fair Value
Investments	$ 457	$ 455