Cash and Cash Equivalents, Investments, and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Jan. 31, 2020	Jul. 31, 2019
Amortized Cost
Due within one year	$ 397	$ 415
Due within two years	216	208
Due within three years	177	163
Due after three years	31	36
Total available-for-sale debt securities	821	822
Fair Value
Due within one year	397	416
Due within two years	218	208
Due within three years	178	164
Due after three years	32	36
Total available-for-sale debt securities	$ 825	$ 824