Cash and Cash Equivalents, Investments, and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Jan. 31, 2019	Jul. 31, 2018
Amortized Cost
Due within one year	$ 285	$ 250
Due within two years	116	117
Due within three years	35	66
Due after three years	23	21
Total available-for-sale debt securities	459	454
Fair Value
Due within one year	284	250
Due within two years	115	116
Due within three years	35	65
Due after three years	24	21
Total available-for-sale debt securities	$ 458	$ 452