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, 2012	Jul. 31, 2011
Cash and Cash Equivalents Items [Line Items]
Due within one year, Amortized Cost	$ 279	$ 267
Due within one year, Fair Value	279	267
Due within two years, Amortized Cost	293	323
Due within two years, Fair Value	295	324
Due within three years, Amortized Cost	188	190
Due within three years, Fair Value	188	191
Due after three years, Amortized Cost	130	151
Due after three years, Fair Value	130	151
Total available-for-sale debt securiites, Amortized Cost	890	931
Total available-for-sale debt securiites, Fair Value	$ 892	$ 933