Cash and Cash Equivalents, Investments, and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Oct. 31, 2019	Jul. 31, 2019
Amortized Cost
Due within one year	$ 382	$ 415
Due within two years	219	208
Due within three years	190	163
Due after three years	30	36
Total available-for-sale debt securities	821	822
Fair Value
Due within one year	383	416
Due within two years	221	208
Due within three years	191	164
Due after three years	30	36
Total available-for-sale debt securities	$ 825	$ 824