Cash and Cash Equivalents, Investments and Funds Held for Customers Type of issue (Details) (USD $) In Millions, unless otherwise specified																	3 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Oct. 31, 2013 Total cash and cash equivalents	Jul. 31, 2013 Total cash and cash equivalents	Oct. 31, 2013 Available-for-sale debt securities [Member]	Jul. 31, 2013 Available-for-sale debt securities [Member]	Oct. 31, 2013 Municipal bonds	Jul. 31, 2013 Municipal bonds	Oct. 31, 2013 Corporate notes	Jul. 31, 2013 Corporate notes	Oct. 31, 2013 U.S. agency securities	Jul. 31, 2013 U.S. agency securities	Oct. 31, 2013 Municipal auction rate securities	Jul. 31, 2013 Municipal auction rate securities	Oct. 31, 2013 Available-for-sale equity securities	Jul. 31, 2013 Available-for-sale equity securities	Oct. 31, 2013 Other long-term investments [Member]	Jul. 31, 2013 Other long-term investments [Member]
Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents, Amortized Cost	$ 417	$ 1,009	$ 216	$ 393	$ 470	$ 1,069
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Amortized Cost Basis	868	860					868	860	499	489	268	269	73	69	28	33
Available-for-sale Equity Securities, Amortized Cost Basis																	5	5
Available-for-sale Securities, Amortized Cost Basis																			17	17
Total cash and cash equivalents investments and funds held for customers	1,360	1,951
Available-for-sale Securities, Fair Value Disclosure	1,389	1,979			470	1,069	870	860	500	489	269	269	73	69	28	33	32	33	17	17
Available-for-sale Securities, Gross Umrealized Gains																	$ 27