Cash and Cash Equivalents, Investments and Funds Held for Customers - Classified by the stated maturity date (Details) - USD ($) $ in Millions	Apr. 30, 2016	Jul. 31, 2015
Available-for-sale Securities, Debt Maturities
Due within one year, amortized cost	$ 189	$ 434
Due within one year, fair value	189	435
Due within two years, amortized cost	125	443
Due within two years, fair value	125	442
Due within three years, amortized cost	75	156
Due within three years, fair value	75	156
Due after three years, amortized cost	125	47
Due after three years, fair value	125	46
Total available-for-sale debt securities, amortized cost	514	1,080
Total available-for-sale debt securities, fair value	$ 514	$ 1,079