Cash and Cash Equivalents, Investments and Funds Held for Customers - Classified by the stated maturity date (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Available-for-sale Securities, Debt Maturities
Due within one year, Amortized Cost	$ 414	$ 363
Due within one year, Fair Value	414	363
Due within two years, Amortized Cost	462	443
Due within two years, Fair Value	462	443
Due within three years, Amortized Cost	160	303
Due within three years, Fair Value	160	303
Due after three years, Amortized Cost	51	120
Due after three years, Fair Value	51	121
Total available-for-sale debt securities, Amortized Cost	1,087	1,229
Total available-for-sale debt securities, Fair Value	$ 1,087	$ 1,230