Cash and Cash Equivalents, Investments, and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Apr. 30, 2020	Jul. 31, 2019
Amortized Cost
Due within one year	$ 386	$ 415
Due within two years	243	208
Due within three years	146	163
Due after three years	21	36
Total available-for-sale debt securities	796	822
Fair Value
Due within one year	387	416
Due within two years	245	208
Due within three years	147	164
Due after three years	21	36
Total available-for-sale debt securities	$ 800	$ 824