Cash and Cash Equivalents, Investments and Funds Held for Customers Classified by the stated maturity date (Details) - USD ($) $ in Millions	Apr. 30, 2017	Jul. 31, 2016
Available-for-sale Securities, Debt Maturities
Due within one year, amortized cost	$ 184	$ 285
Due within one year, fair value	184	285
Due within two years, amortized cost	180	209
Due within two years, fair value	180	210
Due within three years, amortized cost	71	143
Due within three years, fair value	71	143
Due after three years, amortized cost	23	19
Due after three years, fair value	23	19
Total available-for-sale debt securities, amortized cost	458	656
Total available-for-sale debt securities, fair value	$ 458	$ 657