Cash and Cash Equivalents, Investments and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Jan. 31, 2016	Jul. 31, 2015
Available-for-sale Securities, Debt Maturities
Due within one year, amortized cost	$ 89	$ 434
Due within one year, fair value	89	435
Due within two years, amortized cost	41	443
Due within two years, fair value	41	442
Due within three years, amortized cost	45	156
Due within three years, fair value	45	156
Due after three years, amortized cost	15	47
Due after three years, fair value	15	46
Total available-for-sale debt securities, amortized cost	190	1,080
Total available-for-sale debt securities, fair value	$ 190	$ 1,079