Cash and Cash Equivalents, Investments and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Oct. 31, 2016	Jul. 31, 2016
Available-for-sale Securities, Debt Maturities
Due within one year, amortized cost	$ 223	$ 285
Due within one year, fair value	223	285
Due within two years, amortized cost	123	209
Due within two years, fair value	123	210
Due within three years, amortized cost	97	143
Due within three years, fair value	97	143
Due after three years, amortized cost	17	19
Due after three years, fair value	17	19
Total available-for-sale debt securities, amortized cost	460	656
Total available-for-sale debt securities, fair value	$ 460	$ 657