Cash and Cash Equivalents, Investments, and Funds Held for Customers - Table of available-for-sale debt securities classified by maturity date (Details) - USD ($) $ in Millions	Jul. 31, 2021	Jul. 31, 2020
Amortized Cost
Due within one year	$ 551	$ 389
Due within two years	550	256
Due within three years	398	137
Due after three years	5	18
Total available-for-sale debt securities	1,504	800
Fair Value
Due within one year	553	390
Due within two years	551	261
Due within three years	398	139
Due after three years	6	18
Total available-for-sale debt securities	$ 1,508	$ 808