Cash and Cash Equivalents, Investments and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Jan. 31, 2017	Jul. 31, 2016
Available-for-sale Securities, Debt Maturities
Due within one year, amortized cost	$ 185	$ 285
Due within one year, fair value	185	285
Due within two years, amortized cost	168	209
Due within two years, fair value	168	210
Due within three years, amortized cost	93	143
Due within three years, fair value	92	143
Due after three years, amortized cost	15	19
Due after three years, fair value	15	19
Total available-for-sale debt securities, amortized cost	461	656
Total available-for-sale debt securities, fair value	$ 460	$ 657